Pattern formation process

ABSTRACT

A resist composition comprising (a) a polymer having at least repeating units of the formulae:  &lt;IMAGE&gt;  (b) a photoacid generator and (c) a solvent, has high sensitivity to light, excellent heat resistance, adhesiveness to a substrate and suitable for pattern formation with high resolution.

This is a division, of application Ser. No. 07/898,265 filed Jun. 15,1992, now U.S. Pat. No. 5,468,589.

BACKGROUND OF THE INVENTION

This invention relates to a resist material used for production of asemiconductor device, etc. Particularly, the present invention relatesto a resist material for forming a positive pattern using deepultraviolet (DUV) light having a wavelength of 300 nm or less, such asKrF excimer laser beams having a wavelength of 248.4 nm, etc.

In recent years, the wavelength of light from the light source of anexposing apparatus used for micro-fabrication, in particular,photolithography has been shortened with an enhancement of the degree ofintegration of semiconductor devices. Currently, employment of KrFexcimer laser beams (248.4 nm) is being investigated. However, a resistmaterial suitable for this wavelength has not yet been found.

For example, as resist materials used in the case of using a lightsource capable of emitting KrF excimer laser beams or deep ultravioletlight, there have been developed dissolution-inhibiting type resistmaterials comprising a resin having high transmittance for light of near248.4 nm and a photosensitive compound having a diazodiketo group in themolecule (for example, Japanese Patent Unexamined Publication Nos.1-80944, 1-154048, 1-155338, 1-155339 and 1-188852, and Y. Tani et al.,SPIE's 1989 Sympo., 1086-03, etc.). However, thesedissolution-inhibiting type resist materials, in common with oneanother, have a low sensitivity and hence cannot be used in the case ofemployment of deep ultraviolet light or KrF excimer laser beams whichrequires a highly sensitive resist material. On the other hand, forreduction of the amount of exposure energy (enhancement of thesensitivity), there has been proposed recently a chemical amplified typeresist material in which an acid generated by exposure to light is usedas a catalyst H. Ito et al., Polym. Eng. Sci., 23, 1012 (1983)!. On suchchemical amplified type resist materials, various reports have beenpresented for example, H. Ito et al., U.S. Pat. No. 4,491,628 (1985); J.V. Crivello, U.S. Pat. No. 4,603,101 (1986); W. R. Brunsvolt et al.,SPIE's 1989 Sympo., 1086-40; T. Neeman et al., SPIE's 1989 Sympo.,1086-01; and Japanese Patent Unexamined Publication No. 62-115440). Suchchemical amplified type resist materials, however, involve the followingproblems. When there is used in them a phenol ether type resin such aspoly(4-tert-butoxycarbonyloxystyrene),poly(4-tert-butoxycarbonyloxy-α-methylstyrene),poly(4-tert-butoxystyrene), poly(4-tert-butoxy-α-methylstyrene) or thelike, all of the chemical amplified type resist materials have poor heatresistance and are disadvantageous in that because of their low adhesiveproperties to a substrate, film peeling tends to occur duringdevelopment, so that no satisfactory pattern can be obtained. When thereis used a carboxylic acid type resin such aspoly(tert-butyl-4-vinylbenzoate) or the like, the chemical amplifiedtype resist materials are insufficient in light-transmitting propertiesnear 248.4 nm because of the aromatic ring. When there is used apoly(tert-butylmethacrylate) or the like, the heat resistance and dryetching resistance of this resin are poor. A resist material using asilyl group-containing polymer is also disclosed (e.g. Japanese PatentExamined Publication No. 3-44290, etc.). Whenp-trimethyl-silyloxystyrene polymer orp-tert-butylidmethylsilyloxy-styrene polymer is used, there ariseproblems in that the sensitivity is low, complete stripping off of theresist by ashing according to an oxidizing plasma process is impossibledue to containing silicon, etc. Thus, practical application was almostimpossible.

As resist materials free from the above defects, there have recentlybeen reported a resist material obtained by use of a copolymer ofp-tert-butoxycarbonyloxystrene and p-hydroxystyrene (Japanese PatentUnexamined Publication No. 2-209977), resist materials obtained by useof a copolymer of p-tetrahydropyronyloxystyrene and p-hydroxystyrene(Japanese Patent Unexamined Publication Nos. 2-19847, 2-161436 and2-25850), a resist material obtained by use of a copolymer ofp-tert-butoxystyrene and p-hydroxystyrene (Japanese Patent UnexaminedPublication No. 2-62544), etc. However, when these copolymers such asp-tert-butoxycarbonyloxystyrene/p-hydroxystyrene,p-tetrahydropyranyloxystyrene/p-hydroxystyrene,p-tert-butoxystyrene/p-hydroxystyrene, etc. are used as the resincomponent, it is necessary to make a strong acid present as a catalystin order to maintain high sensitivity and to release protective groupssuch as a tert-butoxycarbonyl group, a tetrapyranyl group, a tert-butylgroup, etc. for obtaining alkali solubility. In order to attain such apurpose, there is used a photosensitive compound which generates aremarkably strong acid by exposure to light, e.g. a triphenylphosphoniumsalt, a diphenyliodonium salt,tris(trichloromethyl)-s-triazine/triethanolamine, or the like, in aresist material containing the above-mentioned copolymer as the resincomponent. When a pattern formation is carried out in the presence ofsuch a strong acid, there often takes place a remarkable dimensionalchange of pattern with a time delay between exposure and post exposurebake (PEB), and sometimes no pattern is formed. Thus, even if a patterncan be formed in a remarkably short time, a good pattern formationcannot be expected in a practical production wherein a considerable timeis required from the light exposure to heating treatment.

Further, the above-mentioned photosensitive compounds are generallyunstable, so that resist materials containing them are also poor instorage stability. In any way, there is a problem in that these cannotbe used as they are.

A further problem of the above-mentioned polymers or copolymers is inthat the group used as a protective group for the hydroxyl group (e.g. atert-butoxycarbonyl group, a tert-butyl group, a trimethylsilyl group, atetrahydropyranyl group, etc.) is not completely released even in thepresence of a strong acid. Thus, a polymer or copolymer containing amonomer component having a hydroxyl group protected with such aprotective group is used as a resin component in a resist material, thedifference in dissolution rate for an alkali developer between lightexposed portions and non-exposed portions of the resist material issmall, resulting in insufficient resolution ability.

Although thus the chemical amplified type resist materials have a highersensitivity than do conventional resist materials, they involve problemsof, for example, poor heat resistance of resin, poor adhesive propertiesto a substrate, insufficient transmittance for light of near 248.4 nm,insufficient resolution, and change of the dimensions of a pattern witha time delay between exposure and post exposure bake (PEB). Therefore,they are difficult to put to practical use. Accordingly, there iseagerly desired a practical highly sensitive resist material free fromall of the above problems.

SUMMARY OF THE INVENTION

This invention was made in consideratin of such conditions and isintended to provide a practical positive type resist material(photoresist composition) which is highly pervious to deep ultravioletlight. KrF excimer laser beams, etc., is highly sensitive to exposure bymeans of a source of such light and irradiation with electron beams orX-rays, is very excellent in heat resistance and adhesive properties toa substrate, has high resolution, and can give a highly precise patternwithout a change of the dimensions of the pattern with a time delaybetween exposure and post exposure bake.

This invention provides a photoresist composition comprising (a) apolymer having repeating units of the formula: ##STR2## wherein R¹ is ahydrogen atom or a methyl group; R² and R³ are independently a hydrogenatom, or a linear, branched or cyclic alkyl group having 1 to 6 carbonatoms (except for the case where both R² and R³ are hydrogen atoms), acombination of R² and R³ being able to form a methylene chain having 2to 5 carbon atoms; R⁴ is a linear, branched or cyclic alkyl group having1 to 10 carbon atoms, a linear, branched or cyclic haloalkyl grouphaving 1 to 6 carbon atoms, or an aralkyl group; R⁵ is a hydrogen atomor a cyano group; R⁶ is a hydrogen atom or a methyl group; R⁷ is ahydrogen atom, a cyano group or --COOY (Y is a linear, branched orcyclic alkyl group having 1 to 6 carbon atoms); R⁵ and R⁷ may bind toeach other to form --CO--O--CO--; k and l are independently a naturalnumber (0.1≦k/(k+l)≦0.9); and m is zero or a natural number (when m is anatural number, 0.05≦m/(k+l+m)≦0.50), (b) a photosensitive compoundwhich generates an acid upon exposure to light, and (c) a solventcapable of dissolving the components (a) and (b).

This invention also provides a process for forming a pattern, whichcomprises (i) a step of coating the aforesaid photoresist composition ona substrate, (ii) a step of exposing the coating to light having awavelength of 300 nm or less through a mask after heat treatment, and(iii) a step of developing the coating by use of a developing solutionafter carrying out heat treatment if necessary.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph showing ultraviolet spectrophotometric curves of theindividual polymer films obtained in Example 1.

FIG. 2 is a flow diagram of a process for forming a positive pattern byuse of the photoresist composition of this invention.

FIG. 3 is a cross-sectional view showing "T-shaped" profile observedwhen a positive pattern was formed using the photoresist composition ofComparative Example 1.

FIG. 4 is a cross-sectional view showing the impossibility of patternformation in the case where a positive pattern is attempted to be formedusing each of the photoresist compositions of Comparative Examples 2 to6 and 9.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The polymers used in the photoresist compositions of this invention areas follows.

A polymer having repeating units of the following formula: ##STR3##wherein R¹ is a hydrogen atom or a methyl group; R² and R³ areindependently a hydrogen atom or a linear, branched or cyclic alkylgroup having 1 to 6 carbon atoms (except for the case where both R² andR³ are hydrogen atoms), a combination of R² and R³ being able to form amethylene chain having 2 to 5 carbon atoms; R⁴ is a linear, branched orcyclic alkyl group having 1 to 10 carbon atoms, a linear, branched orcyclic haloalkyl group having 1 to 6 carbon atoms, or an aralkyl group;R⁵ is a hdyrogen atom or a cyano group; R⁶ is a hydrogen atom or amethyl group; R⁷ is a hydrogen atom, a cyano group or --COOY (Y is alinear, branched or cyclic alkyl group having 1 to 6 carbon atoms); R⁵and R⁷ may bind to each other to form --CO--O--CO--; k and l areindependently a natural number (0.1≦k/(k+l)<0.9); and m is zero or anatural number (when m is a natural number, 0.05≦m/(k+l+m)≦0.50).

When m is zero in formula I!, the resulting polymer has repeating unitsrepresented by the formula: ##STR4## wherein R¹, R², R³, R⁴, k and l areas defined above.

More preferably, polymers of formula I! or II! are used in which R¹ is ahydrogen atom; R² is a hydrogen atom or a linear or branched alkyl grouphaving 1 to 6 carbon atoms; R³ is a linear or branched alkyl grouphaving 1 to 6 carbon atoms; and R⁴ is a linear or branched alkyl grouphaving 1 to 10 carbon atoms.

There are also more preferably used polymers of formula I! or II! inwhich R¹ is a hydrogen atom; R² is a hydrogen atom or a methyl group; R³is a methyl group or an ethyl group; and R⁴ is a linear or branchedalkyl group having 1 to 4 carbon atoms.

In formula I! as the alkyl groups having 1 to 6 carbon atoms representedby R² and R³, the alkyl group of the haloalkyl group having 1 to 6carbon atoms represented by R⁴, and the alkyl group having 1 to 6 carbonatoms represented by Y of --COOY represented by R⁷, there can beexemplified methyl group, ethyl group, propyl group, butyl group, amylgroup and hexyl group which may be linear, branched or cyclic. The alkylgroup having 1 to 10 carbon atoms represented by R⁴ includes methylgroup, ethyl group, propyl group, butyl group, amyl group, hexyl group,heptyl group, octyl group, nonyl group and decyl group which may belinear, branched or cyclic. The halogen of the haloalkyl group having 1to 6 carbon atoms represented by R⁴ includes chlorine, bromine, fluorineand iodine. The aralkyl group represented by R⁴ includes, for example,benzyl group, phenethyl group, phenylpropyl group, methylbenzyl group,methylphenethyl group and ethylbenzyl group.

The polymer of formula I! used in this invention has its most markedcharacteristic in that it comprises units having a functional group ofthe formula: ##STR5## Wherein R², R³ and R⁴ are as defined above, whichcan be removed by an acid, namely, an alkoxyalkyl group, ahaloalkoxyalkyl group or an aralkyloxyalkyl group, that is, the polymercomprises monomeric units of the formula: ##STR6## wherein R¹, R², R³and R⁴ are as defined above. In particular, the functional group of theformula VIII! can much more easily be removed by an acid thanconventional functional groups such as tert-butoxycarbonyl group,tert-butyl group, tetrahydropyranyl group, etc., and hence is much moreadvantageous than them for improving the resolution and maintaining thedimensions of a pattern.

Specifically, the monomeric unit of the formula IX! is that derived froma monomer such as p- or m-hydroxystyrene derivative, p- orm-hydroxy-α-methyl-styrene derivative or the like which has a functionalgroup of the formula VIII!. Specific examples of the monomer are p- orm-1-methoxy-1-methylethoxystyrene, p- orm-1-benzyloxy-1-methylethoxystyrene, p or m-1-ethoxyethoxystyrene, p- orm-1-methoxyethoxystyrene, p- or m-1-n-butoxyethoxystyrene, p- orm-1-isobutoxyethoxy-styrene, p- orm-1-(1,1-dimethylethoxy)-1-methylethoxy-styrene, p- orm-1-(1,1-dimethylethoxy)ethoxystyrene, p- orm-1-(2-chloroethoxy)ethoxystyrene, p- or m-1-cyclohexyloxyethoxystyrene,p- or m-1-cyclopentyloxy-ethoxystyrene, p- orm-1-(2-ethylhexyloxy)ethoxystyrene, p- orm-1-ethoxy-1-methylethoxystyrene, p- or m-1-n-propoxyethoxystyrene, p-or m-1-methyl-1-n-propoxy-ethoxystyrene, p- or m-1-ethoxypropoxystyrene,p- or m-1-methoxybutoxystyrene, p- or m-1-methoxycyclo-hexloxystyrene,and p- or m-hydroxy-α-methylstyrene derivatives having the sameprotecting groups as those of the above p- or m-hydroxystyrenederivatives. Of such monomeric units, monomeric units of the formula IX!in which both R² and R³ are alkyl groups (for example, monomeric unitsderived from p- or m-1-methoxy-1-methyl-ethoxystyrene, p- orm-1-benzyloxy-1-methylethoxystyrene, p- orm-1-(1,1-dimethylethoxy)-1-methylethoxystyrene, p- orm-1-ethoxy-1-methylethoxystyrene, p- orm-1-methyl-1-n-propoxyethoxystyrene, etc.) are preferable for theimprovement of the resolution which is one of the objects of thisinvention, because their protecting groups are very easily removable bythe action of an acid. The polymer used in this invention is a copolymercomprising, besides the monomeric units of the above formula IX!,monomeric units of the formula: ##STR7## wherein R¹ is as defined above,and optionally monomeric units of the formula; ##STR8## wherein R⁵,R⁶and R⁷ are as defined above. The monomeric unit of the formula IX! isthat derived from a monomer having a phenolic hydroxyl group. Specificexamples of the monomer are p- or m-vinylphenol and p- orm-hydroxy-α-methylstyrene. As the monomeric units of the formula XI!,i.e., the third component of the polymer used in this invention, therecan be exemplified monomeric units derived from acrylonitrile,fumaronitrile, methyl methacrylate, tert-butyl methacrylate, maleicanhydride, etc.

In the polymer used in this invention (including both of the formulae I!and II!, the ratio of the monomeric units of the formula IX! to themonomeric units of the formula IX! is usually 1:9 to 9:1. Although thepolymer can be used in the photoresist composition of this inventionwhen any ratio is employed in the above range, there is preferablyemployed a ratio of 2:8 to 7:3 which greatly improves the heatresistance of the polymer and the adhesive properties to a substrate.

Specific examples of the polymer used in this invention arep-1-methoxy-1-methylethoxystyrene/p-hydroxystyrene polymers,p-1-benzyloxy-1-methylethoxy-styrene/p-hydroxystyrene polymers,p-1-ethoxyethoxy-styrene/p-hydroxystyrene polymers,p-1-methoxyethoxy-styrene/p-hydroxystyrene polymers,p-1-n-butoxyethoxy-styrene/p-hydroxystyrene polymers,p-1-isobutoxyethoxy-styrene/p-hydroxystyrene polymers,p-1-(1,1-dimethyl-ethoxy)-1-methylethoxystyrene/p-hydroxystyrenepolymers, m-1-(2-chloroethoxy)ethoxystyrene/m-hydroxystyrene polymers,p-1-cyclohexyloxyethoxystyrene/p-hydroxystyrene polymers,m-1-(2-ethylhexyloxy)ethoxystyrene/m-hydroxystyrene polymers,p-1-methoxy-1-methylethoxy-α-methylstyrene/p-hydroxy-α-methylstyrenepolymers, p-1-ethoxyethoxystyrene/p-hydroxystyrene/acrylonitrilepolymers, p-1-ethoxyethoxystyrene/p-hydroxystyrene/fumaronitrilepolymers, p-1-n-butoxyethoxystyrene/p-hydroxystyrene/methyl methacrylatepolymers,p-1-cyclohexyl-1-ethoxyethoxystyrene/p-hydroxystyrene/tert-butylmethacrylate polymers, p-1-methoxycyclohexyloxy-styrene/p-hydroxystyrenepolymers, p-1-ethoxy-1-methylethoxystyrene/p-hydroxystyrene polymers,p-1-cyclopentyloxyethoxystyrene/p-hydroxystyrene polymers,p-1-(2-chloroethoxy)ethoxystyrene/p-hydroxystyrene/tert-butylmethacrylate polymers,m-1-cyclohexyloxyethoxystyrene/m-hydroxystyrene/maleic anhydridepolymers, etc. Needless to say, the polymer used in this invention isnot limited to them.

The polymer used in this invention can easily be obtained, for example,by the following 4 methods.

Method-1!

A monomer of the formula: ##STR9## (wherein R¹, R², R³ and R⁴ are asdefined above) which has a functional group of the above formula VIII!,is subjected alone or together with the third monomer to polymerizationreaction according to a conventional polymer production process at 50°to 110° C. for 1 to 10 hours in a nitrogen or argon stream in an organicsolvent such as benzene, toluene, tetrahydrofuran or 1,4-dioxane in thepresence of a free-radical initiator for example, an azo polymerizationinitiator such as 2,2'-azobis-isobutyronitrile,2,2'-azobis(2,4-dimethylvaleronitrile) or 2,2'-azobis (methyl2-methylpropionate ), or a peroxide type polymerization initiator suchas benzoyl peroxide or lauroyl peroxide!. After completion of thereaction, after-treatment is carried out according to a conventionalpolymer-collecting method to isolate a homopolymer consisting ofmonomeric units of the above formula IX! or a copolymer comprisingmonomeric units of the above formula IX!. Then, the homopolymer or thecopolymer is reacted with a suitable acid preferably, for example, aLewis acid such as sulfuric acid, phosphoric acid, hydrochloric acid orhydrobromic acid, or an organic acid such as p-toluenesulfone acid,malonic acid, oxalic acid! at 30° to 100° C. for 1 to 10 hours in anorganic solvent such as tetrahydrofuran, acetone or 1,4-dioxane toremove the functional group of the above formula VIII! at an optionalrate. After completion of the reaction, after-treatment is carried outaccording to a conventional polymer-collecting method to isolate thedesired polymer.

Method-2!

A monomer having a functional group of the above formula VIII!, p- orm-hydroxystyrene, p- or m- hydroxy-α-methylstyrene and optionally thethird monomer are copolymerized by the same procedure as described inMethod-1. Then, after-treatment is carried out according to aconventional polymer-collecting method to isolate the desired polymer.

Method-3!

Commercially available p-tert-butoxystyrene is subjected alone ortogether with the third monomer to polymerization reaction by the sameprocedure as described in Method-1 to obtain apoly(p-tert-butoxy-styrene) or a copolymer comprisingp-tert-butoxystyrene units. The poly(p-tert-butoxystyrene) or thecopolymer is reacted with a suitable acid preferably, for example, aLewis acid such as sulfuric acid, phosphoric acid, hydrochloric acid orhydrobromic acid, or an organic acid such as p-toluenesulfonic acid,malonic acid, oxalic acid! at 30° to 110° C. for 1 to 20 hours in anorganic solvent such as tetrahydrofuran, acetone or 1,4-dioxane toremove the tert-butyl group, i.e., the functional group completely. Thethus obtained poly(p-hydroxy-styrene) or copolymer comprising monomericunits of the formula X! is reacted with an optional amount of a vinylether compound or an isopropenyl ether compound, which is represented bythe formula: ##STR10## wherein R² and R⁴ are as defined above, at 10° to100° C. for 1 to 20 hours in an organic solvent such astetra-hydrofuran, acetone, 1,4-dioxane, methylene chloride ordimethoxyethane in the presence of a suitable acid e.g. sulfuric acid,hydrochloric acid, p-toluenesulfonic acid, pyridine salt ofchlorosulfonic acid, pyridine salt of sulfuric acid, or pyridine salt ofp-toluenesulfonic acid! to introduce a functional group of the aboveformula VIII! into the poly(p-hydroxystyrene) or the copolymerchemically at an optional rate. Then, after-treatment is carried outaccording to a conventional polymer-collecting method to isolate thedesired polymer.

Method-4!

A commercially available poly(p-hydroxystyrene) is reacted with anoptional amount of a vinyl ether compound or an isopropenyl ethercompound, which is represented by the above formula XIII!, by the sameprocedure as described in Method-3. Then, after-treatment is carried outaccording to a conventional polymer-collecting method to isolate thedesired polymer.

Among the above-mentioned four processes, Method-1 and Method-3 areparticularly preferable which can give a polymer having goodlight-transmitting properties near 248.4 nm. In Method-2 and method-4,p- or m-hydroxystyrene is employed in the polymerization causesoxidation, etc., so that the resulting polymer shows a tendency to lowerlight-transmitting properties near 248.4 nm.

The average molecular weight of the polymer used in this invention isnot critical so long as the polymer can be utilized in the photoresistcomposition. Usually, the weight average molecular weight of the polymeris preferably about 1,000 to about 40,000, more preferably about 3,000to about 25,000, as determined by a GPC measuring method using apolystyrene as a standard.

As the photosensitive compound capable of generating an acid uponexposure to light (hereinafter abbreviated as "photoacid generator")which is used in this invention, any photosensitive compound may be usedso long as it generates an acid upon exposure to light and has noundesirable influence on the formation of a resist pattern. There ispreferably used, in particular, a photoacid generator which has goodlight-transmitting properties near 248.4 nm and hence can maintain thehigh transparency of the photoresist composition, or a photoacidgenerator which is improved in light-transmitting properties in thevicinity of 248.4 nm by exposure to light and hence can maintain thehigh transparency of the photoresist composition. As photo-acidgenerators particularly preferable in this invention, there can beexemplified compounds of the following formula III!, formula V!, formulaVI! or formula VII!: ##STR11## wherein R⁸ and R⁹ are independently alinear, branched or cyclic alkyl group having 1 to 10 carbon atoms, ahaloalkyl group having 1 to 10 carbon atoms, or a group of the formula:##STR12## wherein R¹⁰ and R¹¹ are independently a hydrogen atom, alinear or branched alkyl group having 1 to 5 carbon atoms, or ahaloalkyl group having 1 to 5 carbon atoms which may be either linear orbranched; and n is zero or a natural number. ##STR13## wherein R¹² is alinear, branched or cyclic alkyl group having 1 to 10 carbon atoms, anaralkyl group, a trifluoromethyl group, a phenyl group or a tolyl group;R¹³ and R¹⁴ are independently a hydrogen atom, or a linear or branchedalkyl group having 1 to 5 carbon atoms; and R¹⁵ is a linear, branched orcyclic alkyl group having 1 to 10 carbon atoms, a phenyl group, ahalogen-substituted phenyl group, an alkyl-substituted phenyl group, analkoxy-substituted phenyl group, or an alkylthio-substituted phenylgroup. ##STR14## wherein R¹⁶ is a linear, branched or cyclic alkyl grouphaving 1 to 10 carbon atoms, an aralkyl group, a tri-fluoromethyl group,a phenyl group or a tolyl group; and R¹⁷ is a linear, branched or cyclicalkyl group having 1 to 10 carbon atoms, an aralkyl group or an alkoxygroup. ##STR15## wherein R¹⁸ is a trichloroacetyl group, ap-toluene-sulfonyl group, a p-trifluoromethylbenzenesulfony group, amethanesulfonyl group or a trifluoromethanesulfonyl group; and R¹⁹ andR²⁰ are independently a hydrogen atom, a halogen atom or a nitro group.

Specific examples of photoacid generator preferable in this inventionare bis(p-toluenesulfonyl)-diazomethane, methylsulfonylp-toluenesulfonyldiazo-methane,1-cyclohexylsulfonyl-1-(1,1-dimethylethyl-sulfonyl)diazomethane,bis(1,1-dimethylethylsulfonyl)-diazomethane,bis(1-methylethylsulfonyl)diazomethane,bis(cyclohexylsulfonyl)diazomethane,1-p-toluenesulfonyl-1-cyclohexylcarbonyldiazomethane,2-methyl-2-(p-toluenesulfonyl)propiophenone,2-methanesulfonyl-2-methyl-(4-methylthio)propiophenone,2,4-dimethyl-2-(p-toluenesulfonyl)pentan-3-one,1-diazo-1-methyl-sulfonyl-4-phenyl-2-butanone,2-(cyclohexylcarbonyl)-2-(p-toluenesulfonyl)propane,1-cyclohexylsulfonyl-1-cyclohexylcarbonyldiazomethane,1-diazo-1-cyclo-hexylsulfonyl-3,3-dimethyl-2-butanone,1-diazo-1-(1,1-dimethylethylsulfonyl)-3,3-dimethyl-2-butanone,1-acetyl-1-(1-methylethylsulfonyl)diazomethane,1-diazo-1-(p-toluenesulfonyl)-3,3-dimethyl-2-butanone,1-diazo-1-benzenesulfonyl-3,3-dimethyl-2-butanone,1-diazo-1-(p-toluenesulfonyl)-3-methyl-2-butanone, cyclohexyl2-diazo-2-(p-toluenesulfonyl)acetate, tert-butyl2-diazo-2-benzenesulfonylacetate, isopropyl2-diazo-2-methanesulfonylacetate, cyclohexyl2-diazo-2-benzenesulfonylacetate, tert-butyl2-diazo-2-(p-toluenesulfonyl)acetate, 2-nitrobenzyl p-toluene-sulfonate,2,6-dinitrobenzyl p-toluenesulfonate, 2,4-dinitrobenzylp-trifluoromethylbenzenesulfonate, etc. Needless to say, the photoacidgenerator used in this invention is not limited to them.

As photoacid generators other than the above photoacid generators,various triphenylsulfonium salts and diphenyliodonium salts, etc. haveheretofore been known. But, when they are used as photoacid generatorsin chemical amplified type resist materials, acids (Lewis acids)generated by exposure to light are strong acids and are highly volatile.Therefore, the acids are volatilized from the surface layer of a resistfilm after the exposure to light or are very susceptible to theinfluence of the atmosphere, for example, amine gas atmosphere.Consequently, the following problem, for example, is undesirably causedwith a time delay between exposure and post exposure bake: "T-shaped"profile takes place in pattern formation, the dimensions of a patternare greatly changed, or pattern formation is utterly impossible. Thus,one of the features of the present invention is that the polymer used inthe photoresist composition does not require an acid generatorgenerating such a strong acid.

As the solvent used in this invention, any solvent may be used so longas it can dissolve both the polymer and the photoacid generator.Usually, there are preferably used solvents which cannot absorb light atabout 230 to about 300 nm. Specific examples of the solvent are methylCellosolve acetate, ethyl Cellosolve acetate, propylene glycol monoethylether acetate, methyl lactate, ethyl lactate, 2-ethoxyethyl acetate,methyl pyruvate, ethyl pyruvate, methyl 3-methoxypropionate, ethyl3-methoxypropionate, N-methyl-2-pyrrolidone, cyclohexanone, methyl ethylketone, 1,4-dioxane, ethylene glycol monoisopropyl ether, diethyleneglycol monoethyl ether, diethylene glycol monomethyl ether, diethyleneglycol dimethyl ether, etc. Needless to say, the solvent is not limitedto them. Although the photoresist compositions of this invention usuallycomprise the above three components (the polymer (a), the photoacidgenerator (b) and the solvent (c)) as main constituents, they may, ifnecessary, contain dyes such as fluorenone derivatives, anthracenederivatives, or pyrene derivatives, surfactants or bleaching agents suchas compounds having diazodiketo groups ##STR16## or diazoketo groups##STR17## etc.

A pattern is formed by use of the photoresist composition of thisinvention, for example, as follows.

The photoresist composition comprising the compounds according to thisinvention is coated on a substrate such as silicon wafer to a thicknessof approximately 0.5-2 μm (approximately 0.1 to 0.5 μm when used as atop layer among three layers), and pre-baked in an oven at 70° to 130°C. for 10 to 30 minutes, or on a hot plate at 70° to 130° C. for 1 to 2minutes. Then, a mask for forming a desired pattern is put over theresist film thus formed, and the resist film is irradiated with deepultraviolet light having a wavelength of 300 nm or less, at an exposuredose of approximately 1-100 mJ/cm², followed by baking at 70° to 150° C.for 1 to 2 minutes on a hot plate. Using a developing solution such as a0.1 to 5% aqueous tetramethylammonium hydroxide (TMAH) solution, theresist film is developed for about 0.5 to about 3 minutes by aconventional method such as a dip method, a puddle method or a spraymethod to form the desired pattern on the substrate.

As to the blending proportions of the polymer and the photoacidgenerator according to this invention in a positive type resistmaterial, the proportion of the photoacid generator is 0.01 to 0.3 partby weight, preferably 0.01 to 0.1 part by weight, per part by weight ofthe polymer. The amount of the solvent in the photo-resist compositionof this invention is not critical so long as it does not cause troublewhen a positive type resist material obtained by dissolving the polymerand the photoacid generator according to this invention in the solventis coated on a substrate. The amount is usually 1 to 20 parts by weight,usually about 1.5 to about 6 parts by weight, per part by weight of thepolymer.

As the developing solution used in the above various pattern formationmethods, an alkali solution having a suitable concentration whichdissolves the exposed portion but hardly dissolves the unexposedportion, is chosen depending on the solubility of the polymer used inthe resist material in alkali developing solutions. The concentration ischosen usually in the range of 0.01 to 20%. As the alkali solution used,there can be exemplified solutions containing organic amines such asTMAH, choline, triethanolamine, etc., or inorganic alkalis such as NaOH,KOH, etc.

Since as described above, the polymer used in this invention comprisesmonomeric units of the formula IX! having a functional group of theformula VIII!, it releases the functional group more easily in thepresence of an acid to become alkali-soluble, as compared withconventional polymers used for the same purpose. Therefore, the polymerused in this invention permits stable maintenance of the dimensions of apattern during a delay time between exposure and post exposure bake(PEB). Moreover, since the polymer used in this invention compriseshydroxystyrene units of the formula X!, it has high heat resistance, dryetching resistance and adhesive properties to a substrate. A polymer ofthe formula I! or II! wherein both R² and R³ are hydrogen atoms (themonomeric unit of the formula IX! is that derived from, for example,p-alkoxymethoxystyrene) cannot be used in this invention because when itis used, the photoresist composition acts as a negative resist material.

It was confirmed that in the photoresist compositions of this inventionwhich comprise a photoacid generator of the formula III!, formula IV!,formula VI! or formula VII!, an acid is generated not only byirradiation with KrF excimer laser beams but also by irradiation withelectron beams or X-rays, and causes chemical amplification. Therefore,the photoresist compositions of this invention make it possible to forma pattern by irradiation with deep ultraviolet light, KrF excimer laserbeams (248.4 nm), electron beams or X-rays at a low exposure dose byutilizing a chemical amplification method.

The action of this invention is explained below by giving specificexamples. First, in a portion exposed to KrF excimer laser beams, deepultraviolet light or the like, an acid is generated, for example, by aphoto-reaction represented by the following Equation 1, Equation 2,Equation 3 or Equation 4: ##STR18##

When heat treatment is carried out after the exposure, the specifiedfunctional group (for example, 1-ethoxyethoxy group as in the Equation 5shown below) of the polymer used in this invention is chemically changedby the acid to become a hydroxyl group, according to the followingreaction formula, the Equation 5, and the polymer thus madealkali-soluble is dissolved in a developing solution during development:##STR19##

On the other hand, in the unexposed portion, no acid is generated, sothat the heat treatment does not cause the chemical change. Moreover,the photoacid generator has the effect of protecting the hydrophilicgroup portion of the polymer used for improvement of the adhesiveproperties to a substrate, against infiltration with an alkalideveloping solution. Thus, when a pattern is formed using thephotoresist composition of this invention, there is a large differencebetween the exposed portion and the unexposed portion in solubility inthe alkali developing solution. Furthermore, since the polymer in theunexposed portion has a strong adhesion to a substrate, no film peelingis caused during the development. Consequently, a positive patternhaving a satisfactory contrast is formed. Since the acid generated bythe exposure acts catalytically as shown in the above Equation 5, it issufficient that the exposure is carried out so as to generate anecessary amount of the acid. Therefore, it becomes possible to reducethe amount of exposure energy.

This invention is explained below in further detail with reference toExamples, Synthesis Examples and Comparative Examples, which are not byway of limitation but by way of illustration.

SYNTHESIS EXAMPLE 1 Synthesis of polyp-(1-ethoxyethoxy)styrene/p-hydroxystyrene! Method 1!

(1) Synthesis of p-bromo-(1-ethoxyethoxy)benzene

p-Bromophenol (50 g, 0.29 mole), ethyl vinyl ether (41.7 g, 0.58 mole)and pyridinium p-toluene-sulfonate (1.5 g) were dissolved in methylenechloride (300 ml), followed by reaction with stirring at roomtemperature for 6 hours. Then 5% aqueous sodium bicarbonate (400 ml) wasadded to the reaction mixture, and stirred. Then, the organic layer wasseparated, washed with H₂ O (300 ml×3), dried over anhydrous MgSO₄ andevaporated. The residue (82 g) was distilled under reduced pressure togive 71.1 g of p-bromo-(1-ethoxy-ethoxy)benzene as a pale yellow oilhaving a boiling point of 112°-114° C./6 mmHg.

¹ HNMR δ ppm (CDCl₃): 1.20 (3H, t, J=7 Hz, --CH₂ -C H₃), 1.49 (3H, d,J=5.1 Hz, --OCH--C H₃). 3.47-3.83 (2H, m, --C H₂ CH₃), 5.31-5.37 (1H, q,J=5.5 Hz, OC HCH₃), 6.95 (2H, d, J=8.8 Hz, Aromatic 2-H, 6-H), 7.32 (2H,d, J=8.8 Hz, Aromatic 3-H, 5-H).

IR(Neat) ν cm⁻¹ : 2970, 2930, 2890, 1595, 1490.

(2) Synthesis of p-(1-ethoxyethoxy)styrene

To a suspension of magnesium turning (3.7 g, 0.15 atom) in drytetrahydrofuran (30 ml) under nitrogen, a solution ofp-bromo-(1-ethoxyethoxy)benzene (35 g, 0.14 mole) obtained in above (1)in dry tetrahydrofuran (150 ml) was added dropwise under mild reflux,followed by reaction with stirring for 1 hour under reflux.

After cooling to 10° C, dichloro{1,2-bis(diphenylphosphino)ethane}nickel(0.8 g) was added to the reaction mixture, then a solution of vinylbromide (15.3 g, 0.14 mole) in dry tetrahydrofuran (50 ml) was addeddropwise at 20°-30° C. under nitrogen and continued to stir at roomtemperature for 1 hour. To the reaction mixture, aqueous ammoniumchloride (200 ml) and methylene chloride (200 ml) were added, followedby stirring. Then, the organic layer was separated, washed with H₂ O(200 ml×2), dried over anhydrous MgSO₄ and evaporated. The remaining oil(30 g) was purified by fractional distillation under reduced pressure inthe presence of a few milligrams of tert-butylcatechol as an inhibitor.There was obtained 21.5 g of p-(1-ethoxyethoxy)styrene as a colorlessoil having a boiling point of 93°-96° C.B 1 mmHg.

¹ HNMR δ ppm (CDCl₃): 1.20 (3H, t, J=7Hz, --CH₂ C H₃), 1.50 (3H, d,J=5.1 Hz, OCHC H₃), 3.49-3.85 (2H, m, --C H₂ CH₃), 5.13 (1H, d, J=10.6Hz, C H₂ ═CH--), 5.35-5.41 (1H, q, J=5.5 Hz, O CHCH₃), 5.62 (1H, q,J=17.6 Hz, C H₂ ═C H--), 6.66 (1H, dd, J=10.6 Hz and J=17.6 Hz, CH₂ ═CH--), 6.95 (2H, d, J=8.8 Hz, Aromatic 3-H, 5-H), 7.33 (2H, d, J=8.8 Hz,Aromatic 2-H, 6-H).

IR(Neat) ν cm⁻¹ : 2970, 2930, 2890, 1635 (C═C), 1605, 1505.

Anal. calcd. for C₁₂ H₁₆ O₂ : C %, 74.97; H %, 8.39. Found: C %, 75.08;H %, 8.33.

(3) Free radical polymerization of p-(1-ethoxyethoxy)-styrene

A solution of p- (1-ethoxyethoxy) styrene (19.2 g) obtained in above (2)in toluene containing catalytic amount of 2,2'-azobisisobutyronitrile(AIBN) was polymerized at 80° C. for 6 hours under nitrogen. Aftercooling, the reaction mixture was poured into methanol (1 liter) withstirring, standed, and then decanted. The resultant viscous oil waswashed twice with methanol (500 ml) and concentrated under reducedpressure to give 16.3 g of poly p-(1-ethoxyethoxy)styrene! as a paleyellow viscous oil having Mw 10000 and Mn 5500 (GPC with polystyrenecalibration).

(4) Synthesis of poly p-(1-ethoxyethoxy)styrene-hydroxystyrene!

A solution of poly p-(1-ethoxyethoxy)styrene! (15.5 g) obtained in above(3) and oxalic acid (1.6 g) in 1,4-dioxane (150 ml) was reflux for 3hours with stirring. The mixture was cooled, poured into H₂ O (1 liter)and the solid was precipitated. The precipitate was filtered, washedwith H₂ O and dried under reduced pressure to afford 12.0 g of the titlecompound as a white powder having Mw 8500, Mw/Mn≈ca. 1.8 (GPC withpolystyrene calibration). The polymer was found to havep-(1-ethoxyethoxy)styrene unit and p-hydroxystyrene unit in a molarratio of ca. 1:1 based on ¹ HNMR analysis (with calibration using themethine proton at δ 5.25-5.4 ppm and the aromatic proton at δ 6.2-6.8ppm in the ¹ HNMR spectrum.)

SYNTHESIS EXAMPLE 2 Synthesis of poly p-(1-ethoxyethoxy)styrene/p-hydroxystyrene! Method 2!

Using p-(1-ethoxyethoxy)styrene (9.6 g) obtained in Synthesis Example 1,(2) and p-hydroxystyrene (6.0 g), free radical polymerization wascarried out in the same manner as described in Synthesis Example 1, (3).Then the reaction mixture was poured into petroleum ether (1 liter), andthe precipitate was filtered, washed and dried in vacuo to afford 12.8 gof the title compound as a white powder having Mw 9000 and Mw/Mn=2.0(GPC with polystyrene calibration). The polymer was found to havep-(1-ethoxyethoxy)styrene unit and p-hydroxystyrene unit in a molarratio of ca. 1:1 based on ¹ HNMR.

SYNTHESIS EXAMPLE 3 Synthesis of polyp-(1-ethoxy-ethoxy)styrene/p-hydroxystyrene! Method 3!

(1) Free radical polymerization of p-tert-butoxystyrene

A solution of p-tert-butoxystyrene (17.6 g) in toluene containingcatalytic amount of 2,2'-azobis-isobutyronitrile (AIBN) was polyemrizaedat 80° C. for 6 hours under nitrogen. After cooling, the reactionmixture was poured into methanol (1 liter) and the polymer wasprecipitated. The polymer was filtered, washed with methanol and driedunder reduced pressure to afford 15.5 g of poly(p-tert-butoxystyrene) asa white powder having Mw 10000 (GPC with polystyrene calibration).

(2) Synthesis of poly(p-hydroxystyrene)

A solution of poly(p-tert-butoxystyrene) (15.0 g) obtained in above (1)and conc. hydrochloric acid (10 ml) in 1,4-dioxane was refluxed for 4hours with stirring. The mixture was cooled, poured into H₂ O (1 liter)and the solid was precipitated. The polymer was filtered, washed with H₂O and dried under reduced pressure to give 9.7 g ofpoly(p-hydroxystyrene) as a white powder.

(3) Synthesis of poly p-(1-ethoxyethoxy)styrene/p-hydroxystyrene!

To a solution of poly(p-hydroxystyrene) (4.0 g) obtained in above (2)and ethyl vinyl ether (1.5 g) in a mixed solvent (35 ml) of pyridine and1,4-dioxane, a catalytic amount of p-toluenesulfonic acid was added andreacted with stirring at room temperature for 24 hours. The reactionmixture was poured into H₂ O (1 liter) and a white solid wasprecipitated. The polymer was filtered, washed with H₂ O and dried underreduced pressure to afford 5.0 g of the desired product as a whitepowder having Mw 10000 (GPC with polystyrene calibration). The polymerwas found to have p-(1-ethoxyethoxy)styrene unit and p-hydroxystyreneunit in a molar ratio of ca. 1:1 based on ¹ HNMR.

SYNTHESIS EXAMPLE 4 Synthesis of poly p-(1-ethoxyethoxy)styrene/p-hydroxystyrene! Method 4 !

A solution of poly(p-hydroxystyrene) (8.0 g) MARUKA LYNCUR-M,manufactured by Maruzene Petrochemical Co., Ltd., having Mw 10000 and Mn5000!, ethyl vinyl ether (3.0 g) and pyridinium p-toluenesulfonate (0.5g) in dioxane (70 ml) was reacted with stirring at room temperature for24 hours. After reaction, the mixture was poured into H₂ O, wasprecipitated with stirring, and the precipitate was filtered, washedwith H₂ O and then dried in vacuo. There was obtained 10.0 g of thedesired product as a white powder having Mw 11000 (GPC with polystyrenecalibration). The polymer was found to have p-(1-ethoxyethoxy)styreneunit and p-hydroxystyrene unit in a molar ratio of ca. 1:1 based on ¹HNMR.

SYNTHESIS EXAMPLE 5 Synthesis of polyp-(1-ethoxy-ethoxy)styrene/p-hydroxystyrene!

To a solution of poly(p-hydroxystyrene) (4.0 g) obtained in SynthesisExample 3, (2) and ethyl vinyl ether (1.5 g) in acetone, a catalyticamount of pyridinium p-toluenesulfonate was added, and reacted withstirring at room temperature for 12 hours. The reaction mixture waspoured into H₂ O (1 liter) and was precipitated. The precipitate wasfiltered, washed with H₂ O and dried under reduced pressure to give 3.9g of the desired product as a white powder having Mw 10000 (GPC withpolystyrene calibration). The polymer was found to havep-(1-ethoxyethoxy)styrene unit and p-hydroxystyrene unit in a molarratio of ca. 35:65 based on ¹ HNMR.

SYNTHESIS EXAMPLE 6 Synthesis of poly p-(1-methoxyethoxy)styrene/p-hydroxystyrene! Method 1!

(1) Synthesis of p-bromo-(1-methoxyethoxy)benzene

Using p-bromophenol (17.3 g, 0.1 mole) and methyl vinyl ether (14.0 g,0.2 mole), the reaction was carried out in the same manner as describedin Synthesis Example 1, (1), and the crude oil (24 g) was purified bydistillation under reduced pressure to afford 20.8 g ofp-bromo-(1-methoxyethoxy)benzene as a pale yellow oil having a boilingpoint 89°-90° C./2 mmHg.

¹ HNMR δ ppm (CDCl₃): 1.46 (3H, d, J=5 Hz, OCHC H₃), 3.37 (3H, s,--OCH₃), 5.29 (1H, q, J=5.5 Hz, O CHCH₃), 6.86 (2H, d, J=8 Hz, Aromatic2-H, 6-H), 7.36 (2H, d, J=8.8 Hz, Aromatic 3-H, 5-H).

IR(Neat) ν cm⁻¹ : 3000, 2940, 2850, 1590, 1580, 1490.

(2) Synthesis of p-(1-methoxyethoxy)styrene

Using p-bromo-(1-methoxyethoxy)benzene (11.6 g) obtained in above (1),the reaction was carried out in the same manner as described inSynthesis Example 1, (2), and the crude oil (10.7 g) was distilled underreduced pressure in the presence of a few milligrams ofp-tert-butylcatechol as an inhibitor to give 8.8 g ofp-(1-methoxyethoxy)styrene as a colorless oil having a boiling point of86°-87° C.B 3 mmHg.

¹ HNMR δ ppm (CDCl₃): 1.46 (3H, d, J=5.5 Hz, OCHC H₃), 3.37 (3H, s, CH₃), 5.12 (1H, d, J═11 Hz, C H₂ ═CH--), 5.30 (1H, q, J═5.1 Hz and J═5.5Hz, O CHCH₃), 5.60 (1H, d, J═17.6 Hz, C H₂ ═CH--), 6.64 (1H, dd, J═11 Hzand J═17.6 Hz, C H₂ ═C H--), 6.95 (2H, d, J═8.8 Hz, Aromatic 3-H, 5-H),7.32 (2H, d, J═8.8 Hz, Aromatic 2-H, 6-H).

IR(Neat) ν cm⁻¹ : 2980, 2920, 2820, 1620 (C═O), 1600, 1500.

Anal. calcd. for C₁₁ H₁₄ O₂ : C %, 74.13; H %, 7.92. Found: C %, 74.41;H %, 7.88.

(3) Free radical polymerization of p-(1-methoxyethoxy)-styrene

Using p-(1-methoxyethoxy)styrene (8.0 g) obtained in above (2), thepolymerization was carried out in the same manner as described inSynthesis Example 1, (3), and the resultant viscous oil was washed withmethanol and concentrated in vacuo to give 7.2 g ofpoly(1-methoxyethoxy)styrene as a pale yellow viscous oil having Mw10000 and Mn 5000 (GPC with polystyrene calibration).

(4) Synthesis of poly p-(1-methoxyethoxy)styrene-hydroxystyrene!

Using poly(1-methoxyethoxy)styrene (6.2 g) obtained in above (3), thereaction was carried out in the same manner as described in SynthesisExample 1, (4) to afford 3.0 g of the title compound as a white powderhaving Mw 9000 and Mw/Mn≈1.8 (GPC with polystyrene calibration). Thecomposition of the polymer was found to be p-(1-methoxyethoxy)styreneunit and p-hydroxystyrene unit in a molar ratio of ca. 45:55 based on ¹HNMR.

SYNTHESIS EXAMPLE 7 Synthesis of polyp-(1-methoxy-1-methylethoxy)styrene/p-hydroxy styrene!

To a solution of poly(p-hydroxystyrene) (4.0 g) obtained in the samemanner as described in Synthesis Example 3, (2) and 2-methoxy-1-propene(4.8 g) in a mixed solvent (35 ml) of pyridine and 1,4-dioxane, acatalytic amount of chlorosulfonic acid was added and then reacted withstirring at room temperature for 20 hours. After reaction, the reactionwas carried out in the same manner as described in Synthesis Example 2,(3) to give 4.1 g of polyp-(1-methoxy-1-methylethoxy)styrene/p-hydroxystyrene as a white powderhaving Mw 10000 (GPC with polystyrene calibration). The composition ofthe polymer was found to be p-(1-methoxy-1-methylethoxy)styrene unit andp-hydroxystyrene unit in a molar ratio of ca. 1:1 based on ¹ HNMR.

SYNTHESIS EXAMPLE 8 Synthesis of poly p-(1-n-butoxyethoxy)styrene/p-hydroxystyrene!

To a solution of poly(p-hydroxystyrene) (4.8 g) obtained in the samemanner as described in Synthesis Example 3, (2) and n-butyl vinyl ether(3.0 g) in a mixed solvent (50 ml) of pyridine and 1,4-dioxane, acatalytic amount of conc. sulfuric acid was added, then continued tostir at room temperature for 16 hours. The reaction mixture was treatedin the same manner as described in Synthesis Example 2, (3) to give 4.2g of poly p-(1-n-butoxyethoxy)styrene/p-hydroxystyrene! as a whitepowder having Mw 10000 (GPC with polystyrene calibration). Thecomposition of the polymer was found to be p-(1-n-butoxyethoxy)styreneunit and p-hydroxystyrene unit in a molar ratio of 4:6 based on ¹ HNMR.

SYNTHESIS EXAMPLE 9 Synthesis of polyp-(1-ethoxyethoxy)styrene/p-hydroxystyrene/fumaronitrile!

(1) Free radical polymerization of p-tert-butoxy-styrene andfumaronitrile

A solution of p-tert-butoxystyrene (28.2 g, 0.16 mole) and fumaronitrile(3.1 g, 0.04 mole) in toluene containing catalytic amount of 2,2'-azobis(methyl 2-methylpropionate) was heated at 90° C. for 2 hours undernitrogen. After reaction, the reaction mixture was poured into methanolto precipitate a polymer. The polymer was filtered, washed and dried invacuo to give 21.3 g of poly(p-tert-butoxystyrene-fumaronitrile) as awhite powder.

(2) Synthesis of poly(p-hydroxystyrene/fumaronitrile)

Using poly(p-tert-butoxystyrene/fumaronitrile) (20.0 g) obtained inabove (1), the reaction was carried out in the same manner as describedin Synthesis Example 3, (2) to afford 10.6 g of the desired product as awhite powder having Mw 10000 (GPC with polystyrene calibration).

(3) Synthesis of polyp-(1-ethoxyethoxy)styrene/p-hydroxystyrene/fumaronitrile!

Using poly(p-hydroxystyrene/fumaronitrile) (9.0 g) obtained in above (2)and ethyl vinyl ether (3.0 g), the reaction was carried out in the samemanner as described in Synthesis Example 3, (3) to give 8.8 g of thedesired product as a white powder having Mw 11000 (GPC with polystyrenecalibration). The composition of the polymer was found to bep-(1-ethoxyethoxy)styrene unit and p-hydroxystyrene unit in a molarratio of ca. 4:6 based on ¹ HNMR.

SYNTHESIS EXAMPLE 10 Synthesis of polyp-(1-ethoxyethoxy)styrene/p-hydroxystyrene/tert-butyl methacrylate!

(1) Free radical polymerization of p-(1-ethoxyethoxy) styrene andtert-butyl methacrylate!

A solution of p-(1-ethoxyethoxy)styrene (17.3 g, 0.09 mole) obtained inSynthesis Example 1, (2) and tert-butyl methacrylate (1.4 g, 0.01 mole)in toluene containing catalytic amount of 2,2'-azobis(methyl2,4-dimethylpropionate) was heated at 80° C. for 8 hours under nitrogen.After cooling, the reaction mixture was poured into petroleum ether withstirring, standed, and then decanted. The resultant viscous oil waswashed twice with methanol (500 ml) and concentrated under reducedpressure to give 15.5 g of poly p-(1-ethoxyethoxy)-styrene/tert-butylmethacrylate! as a pale yellow viscous oil having Mw 12000 (GPC withpolystyrene calibration).

(2) Synthesis of polyp-(1-ethoxyethoxy)styrene/p-hydroxystyrene/tert-butyl methacrylate!

A solution of poly p-(1-ethoxyethoxy)styrene/tert-butyl methacrylate!(12.0 g) obtained in above (1) in 1,4-dioxane, was added withp-toluenesulfonic acid (0.5 g) and reacted with stirring at 80° C. for30 minutes. After cooling, the reaction mixture was poured into H₂ O (1liter) to precipitate a polymer. The polymer was filtered by suction,washed with H₂ O and dried in vacuo to give 9.8 g of the desired productas a white powder having Mw 11000 (GPC with polystyrene calibration).The composition of the polymer was found to be p-(1-ethoxyethoxy)styreneunit and p-hydroxystyrene unit in a molar ratio of ca. 35:65 based on ¹HNMR analysis.

REFERENCE EXAMPLE 1 Synthesis ofpoly(p-tetrahydropyranylstyrene/p-hydroxystyrene)

To a solution of poly(p-hydroxystyrene) (9.0 g) MARUKA LYNCUR-M,manufactured by Maruzen Petrochemical Co., Ltd., Mw 10000 and Mn 5000!in dimethoxyethane (100 ml), 3,4-dihydro-2H-pyran (12.6 g) and conc.sulfuric acid (0.5 ml) were added, followed by reaction at 30°-40° C.for 15 hours with stirring. After reaction, the mixture was evaporatedin vacuo, the residue was neutralized by addition of sodium carbonateand poured into H₂ O (1 liter). The precipitate was filtered by suction,washed with H₂ O and dried under reduced pressure to give 11.0 g of thetitle compound as a white powder having Mw 10000 (GPC with polystyrenecalibration). The composition of the polymer was found to bep-tetrahydro-pyranyloxystyrene unit and p-hydroxystyrene unit in a molarratio of ca. 3:7 based on ¹ HNMR.

REFERENCE EXAMPLE 2 Synthesis ofpoly(p-tert-butoxystyrene/p-hydroxystyrene)

To a solution of poly(p-hydroxystyrene) (4.0 g) MARUKA LYNCUR-M,manufactured by Maruzen Petrochemical Co., Ltd., Mw 10000 and Mn 5000!in dimethoxyethane (70 ml) in a pressure vessel, isobutyrene (60 g) andconc. sulfuric acid (0.3 g) were added at -60° C. or lower. The mixturewas brought to 45° C. for 1 hour with stirring, and then stirring wascontinued at room temperature for 22 hours. After reaction, the mixturewas evaporated, and the residue was neutralized by sodium carbonate andpoured into H₂ O. The precipitate was filtered by suction, washed was H₂O and dried in vacuo to give 4.1 g ofpoly(p-tert-butoxystyrene/p-hydroxystyrene) as a white powder having Mw10000 (GPC with polystyrene calibration). ¹ HNMR analysis indicated that50% of p-hydroxy group was converted into p-tert-butoxy group.

REFERENCE EXAMPLE 3 Synthesis ofpoly(p-tert-butoxycarbonyloxystyrene/p-hydroxy-styrene)

(1) A solution of p-tert-butoxycarbonyloxystyrene (22 g, 0.1 mole)obtained by the method of U.S. Pat. No. 4,491,628 (1985) in toluenecontaining catalytic amount of 2,2'-azobis(2,4-dimethylvaleronitrile)was heated at 90° C. for 4 hours under nitrogen. After cooling, thereaction mixture was poured into methanol and polymer was precipitated.The polymer was filtered, washed with methanol and dried under reducedpressure to give 15.2 g of poly(p-tert-butoxycarbonyloxystyrene) as awhite powder having Mw 12000 (GPC with polystyrene calibration).

(2) To a solution of poly(p-tert-butoxy-carbonyloxystyrene) (7.0 g)obtained in above (1) in 1,4-dioxane, conc. hydrochloric acid (5 ml) wasadded and continued to stir under reflux for 1.5 hours. After cooling,the reaction mixture was poured into H₂ O (1 liter) and the polymer wasprecipitated. The polymer was filtered by suction, washed with H₂ O anddried in vacuo to afford 4.8 g ofpoly(p-tert-butoxycarbonyloxy-styrene/p-hydroxystyrene) as a whitepowder having Mw 9500 (GPC with polystyrene calibration). Thecomposition of the polymer was found to bep-tert-butoxycarbonyloxy-styrene unit and p-hydroxystyrene unit in amolar ratio of ca. 1:1 based on ¹ HNMR analysis.

REFERENCE EXAMPLE 4 Synthesis of 2-cyclocarbonyl-2-(p-toluenesulfonyl)propane

(1) To a suspension of magnesium turning (23.9 g, 0.98 atom) in dryethyl ether, cyclohexylbromide (160 g, 0.98 mole) was added dropwiseunder mild reflux, followed by reaction with stirring for 1 hour underreflux to afford Grignard reagent. After cooling, the Grignard reagentwas added dropwise to a solution of isobutyloyl chloride (95 g, 0.89mole) in dry ethyl ether at -5°-0° C., the resultant mixture was stirredat the same temperature for 3 hours and standed at room temperatureovernight. The reaction mixture was poured into H₂ O, and the organiclayer was separated, washed with H₂ O, dried over anhydrous MgSO₄ andevaporated. The residue was distilled under reduced pressure to give 50g of 1-cyclohexyl-2-methyl-1-propanone as a pale yellow oil having aboiling point of 95°-100° C./20 mmHg

¹ HNMR δ ppm (CDCl₃): 1.06 (6H, d, C H₃ ×2), 1.12-1.87 (10H, m,cyclohexylic C H₂ ×5), 2.51 (1H, m, cyclohexylic C H), 2.76 (1H, m, C H)

IR(Neat) ν cm⁻¹ : 1710 (C═O).

(2) To 1-cyclohexyl-2-methyl-1-propanone (47.6 g, 0.31 mole) obtained inabove (1), sulfuryl chloride (42 g, 0.31 mole) was added dropwise at25°-35° C. The mixture was stirred at 50° C. for 3.5 hours and thenevaporated. The resultant residue was distilled under reduced pressureto give 30.1 g of 2-chloro-1-cyclohexyl-2-methyl-1-propanone as a yellowoil having a boiling point of 99°-105° C.B 18 mmHg.

¹ HNMR δ ppm(CDCl₃): 1.18-1.87 (16H, m, C H₃ ×2 and cyclohexylic C H₂×5), 3.13 (1H, m, cyclohexylic C H).

(3) A solution of 2-chloro-1-cyclohexyl-2-methyl-1-propanone (30.3 g,0.16 mole) obtained in above (2) and sodium p-toluenesulfinate (30.0 g,0.17 mole) in dimethylsulfoxide (320 ml) was reacted with stirring at60° C. for 20 hours. The reaction mixture was poured into cold H₂ O,continued to stir at 0°-5° C. for 1 hour. The precipitate was filtered,washed with H₂ O and dried. The crude solid (18 g) was recrystallizedfrom n-hexaneenzene to give 13.5 g of2-cyclohexylcarbonyl-2-(p-toluenesulfonyl)propane as white needles, m.p.123°-123.5° C.

¹ HNMR δ ppm (CDCl₃): 1.19-1.91 (16H, m, C H₃ ×2 and cyclohexylic C H₂×5), 2.45 (3H, s, Ph-C H₃), 3.25 (1H, m, cyclohexylic C H), 7.33 (2H, d,J=8 Hz, Aromatic 3-H, 5-H), 7.65 (2H, d, J=8 Hz, Aromatic 2-H, 6-H).

IR(KBr-disk) ν cm⁻¹ : 1705 (C═O), 1310

REFERENCE EXAMPLE 5 Synthesis of2-methyl-2-(p-toluenesulfonyl)propiophenone

Using isobutyrophenone (29.6 g, 0.2 mole), the reaction was carried outin the same manner as described in Reference Example 4, (2) and (3). Thecrude solid was recrystallized from methanol to afford 21.2 g of2-methyl-2-(p-toluenesulfonyl)propiophenone as white needles having amelting point of 64°-64.5° C.

¹ HNMR δ ppm (CDCl₃): 1.70 (6H, s, C H₃ ×2), 2.45 (3H, s, Ph-C H₃), 7.32(2H, d, J=7 Hz, p-Tolyl 3-H, 5-H), 7.44 (2H, t, J=7 Hz, Aromatic 3-H,5-H), 7.54 (1H, t, J=7 Hz, Aromatic 4-H), 7.67 (2H, d, J=7 Hz, p-Tolyl2-H, 6-H), 7.95 (2H, d, J=8 Hz, Aromatic 2-H, 6-H).

IR(KBr-disk) ν cm⁻¹ : 1680 (C═O), 1303, 1290.

REFERENCE EXAMPLE 6 Synthesis of 2,4-dimethyl-2-(p-toluenesulfonyl)pentan-3-one

Using diisopropylketone (22.8 g, 0.2 mole), the reaction was carried outin the same manner as described in Reference Example 4, (2) and (3). Thecrude solid was recrystallized from n-hexaneenzene to afford 16.5 g of2,4-dimethyl-2-(p-toluenesulfonyl)pentan-3-one as white leaflets, m.p.76°-79° C.

¹ HNMR δ ppm (CDCl₃): 1.15 (6H, d, C H₃ ×2), 1.55 (6H, s, C H₃ ×2), 2.45(3H, s, Ph-C H₃), 3.54 (1H, m, J=7 Hz, C H), 7.34 (2H, d, J=8 Hz,Aromatic 3-H, 5-H), 7.65 (2H, d, J=8 Hz, Aromatic 2-H, 6-H).

REFERENCE EXAMPLE 7 Synthesis of bis(cyclohexylsulfonyl)diazomethane

(1) After dissolving sodium azide (22.5 g, 0.35 mole) in a small amountof H₂ O, the resulting solution was diluted with a 90% ethanol aqueoussolution (130 ml). To this, a solution of p-toluenesulfonyl chloride (60g, 0.32 mole) in ethanol (300 ml) was added dropwise at 10°-25° C.,followed by reaction at room temperature for 2.5 hours. The reactionsolution was concentrated at room temperature under reduced pressure.The resulting oily residue was washed several times with H₂ O and driedover anhydrous MgSO₄. After removing the drying agent by filtration,there was obtained 50.7 g of p-toluene-sulfonylazide as a colorless oil.

¹ HNMR δ ppm (CDCl₃): 2.43 (3H, s, C H₃), 7.24 (2H, d, J=8 Hz, Aromatic3-H, 5-H), 7.67 (2H, d, J=8 Hz, Aromatic 2-H, 6-H).

IR(Neat) ν cm⁻¹ : 2120 (-N₃).

(2) To cyclohexylthiol (20.2 g, 0.17 mole), a solution of potassiumhydroxide (12.0 g, 0.21 mole) in ethanol (50 ml) was added dropwise atroom temperature and mixture was stirred at 30°±5° C. for 30 minutes.Then methylene chloride (18.2 g, 2.14 mole) was added to this mixtureand reacted with stirring at 50°±5° C. for 6 hours. After standing atroom temperature overnight, the reaction mixture was diluted withethanol (55 ml) and added with sodium tungstate (0.4 g). Then, 30%hydrogen peroxide (50 g, 0.44 mole) was added dropwise to this solutionat 45°-50° C., then reacted with stirring for 4 hours at the sametemperature, added with H₂ O (200 ml) and standed at room temperatureovernight. The precipitate was filtered, washed with H₂ O and dried. Theresultant solid (22 g) was recrystallized from ethanol to give 15.5 g ofbis(cyclohexylsulfonyl)methane as white needles, m.p. 137°-139° C.

¹ HNMR δ ppm (CDCl₃): 1.13-2.24 (20H, m, cyclohexylic C H₂ ×10),3.52-3.66 (2H, m, cyclohexylic C H×2), 4.39 (2H, s, C H₂).

IR(KBr-disk) ν cm⁻¹ : 1320, 1305.

(3) To a solution of sodium hydroxide (1.7 g) in a 60% ethanol aqueoussolution (70 ml), bis(cyclohexyl-sulfonyl) methane (12.1 g, 0.04 mole)obtained in above (2) was added, then a solution ofp-toluenesulfonylazide (8.2 g, 0.04 mole) obtained in above (1) inethanol (10 ml) was added dropwise at 5°-10° C., followed by thereaction at room temperature for 7 hours. After standing at roomtemperature overnight, the precipitate was filtered, washed with ethanoland dried. The resultant residue (11 g) was recrystallized fromacetonitrile to give 8.0 g of bis(cyclohexylsulfonyl)diazomethane as apale yellow prisms having a melting point of 130°-131° C.

¹ HNMR δ ppm (CDCl₃): 1.13-2.25 (20H, m, cyclohexylic C H₂ ×10),3.36-3.52 (2H, m, cyclohexylic C H×2).

IR(KBr-disk) ν cm⁻¹ : 2130 (CN₂), 1340, 1320.

REFERENCE EXAMPLE 8 Synthesis of methylsuflonylp-toluenesulfonyldiazomethane

(1) To a solution of methylthiomethyl p-tolyl-sulfone (6.0 g, 0.03 mole)and sodium tungstate (60 mg) in methanol (40 ml) and H₂ O (40 ml), 30%hydrogen peroxide (6.8 g, 0.06 mole) was added dropwise at 45°-50° C.,reacted with stirring for 10 hours under reflux, and standed at roomtemperature overnight. The reaction mixture was poured into H₂ O (400ml), and the precipitate was filtered, washed with H₂ O and dried. Thecrude solid (7.2 g) was recrystallized from ethanol to afford 6.1 g ofmethylsulfonyl p-toluenesulfonylmethane as white needles, m.p.163.5°-165° C.

¹ HNMR δ ppm (CDCl₃): 2.48 (3H, s, Ph-C H₃), 3.28 (3H, s, C H₃), 4.56(2H, s, C H₂), 7.40 (2H, d, J=8 Hz, Aromatic 3-H, 5-H), 7.87 (2H, d, J=8Hz, Aromatic 2-H, 6-H).

(2) Using methylsulfonyl p-toluenesulfonylmethane (5.0 g, 0.02 mole)obtained in above (1), the reaction was carried out in the same manneras described in Reference Example 7, (3). The crude solid (3 g) wasrecrystallized from ethanol to give 2.2 g of methyl-sulfonylp-toluenesulfonyldiazomethane as pale yellow leaflets having a meltingpoint of 107.5°-109° C.

¹ HNMR δ ppm (CDCl₃): 2.46 (3H, s, Ph-C H₃), 3.42 (3H, s, C H₃), 7.38(2H, d, J=8 Hz, Aromatic 3-H, 5-H), 7.87 (2H, d, J=8 Hz, Aromatic 2-H,6-H).

IR(KBr-disk) ν cm⁻¹ : 2120 (CN₂), 1350, 1330.

REFERENCE EXAMPLE 9 Synthesisbis(1,1-dimethylethyl-sulfonyl)diazomethane

Using tert-butylmercaptan (18.0 g, 0.2 mole), the reaction and treatmentwere carried out in the same manner as described in Reference Example 7,(2) and (3). The crude solid was recrystallized from ethanol to give 8.5g of bis(1,1-dimethylethyl sulfonyl)diazomethane as pale yellow needles,m.p. 121°-121.5° C.

¹ HNMR δ ppm (CDCl₃): 1.52 (18H, s, C H₃ ×6).

IR(KBr-disk) ν cm⁻¹ : 2120 (CN₂), 1330, 1315.

REFERENCE EXAMPLE 10 Synthesis of 1-diazo-1-cyclohexylsulfonyl-3,3-dimethyl-2-butanone

(1) To cyclohexylthiol (23 g, 0.198 mole), a solution of potassiumhydroxide (13.7 g, 0.207 mole) in ethanol (80 ml) was added dropwise at15° C., followed by stirring at the same temperature for 24 hours. After1-bromo-3,3-dimethyl-2-butanone (35.4 g, 0.198 mole) was added dropwiseto the reaction mixture at 10°-15° C. and continued to stir at 20° C.for 5 hours, sodium tungstate (2.5 g) was added. Then, 30% hydrogenperoxide (220 g, 1.96 mole) was added dropwise at 45°-50° C. and reactedwith stirring at 60°-80° C. for 30 hours. After cooling, the reactionmixture was extracted with methylene chloride (300 ml×1), the organiclayer was separated, dried over anhydrous MgSO₄ and evaporated to obtain14 g of residual crude 1-cyclohexylsulfonyl-3,3-dimethyl-2-butanone as apale yellow oil.

¹ HNMR δ ppm (CDCl₃): 1.10-2.19 (19H, m, C H₃ ×3 and cyclohexylic C H₂×5), 3.37-3.53 (1H, m, cyclohexylic C H), 4.12 (2H, s, C H₂).

IR(Neat) ν cm⁻¹ : 1700 (C═O), 1310.

(2) To a solution of crude 1-cyclohexylsulfonyl-3,3-dimethyl-2-butanone(13 g, 0.053 mole) obtained in above (1) and triethylamine (6.14 g,0.061 mole) in ethanol (40 ml), p-toluenesulfonylazide (11.4 g, 0.058mole) obtained in Reference Example 7, (1) was added dropwise at 0°-5°C., and continued to stir at 10°-20° C. for 8 hours. After standing atroom temperature overnight, the reaction mixture was evaporated invacuo. The residue was diluted with ethyl ether (250 ml), and theorganic layer was washed with 5% potassium hydroxide aqueous solution(100 ml×2) and then brine (100 ml×1), dried over anhydrous MgSO₄ andevaporated. The residue (15 g) was chromatographed on silica gel(Wakogel C-200, manufactured by Wako Pure Chemical Industries, Ltd.)with n-hexaneethylene chloride (7/1→4/1→2/1) as eluent andrecrystallized from n-hexane/ethyl ether to give 2.5 g of1-diazo-1-cyclohexylsulfonyl-3,3-dimethyl-2-butanone as pale yellowneedles, m.p. 80.5°-82.0° C.

¹ HNMR δ ppm (CDCl₃): 1.05-2.16 (19H, m, C H₃ ×3 and cyclohexylic C H₂×5), 3.52-3.66 (1H, m, cyclohexylic C H)

IR(KBr-disk) ν cm⁻¹ : 2105 (CN₂), 1650 (C═O), 1320 (SO₂).

REFERENCE EXAMPLE 11 Synthesis of1-diazo-1-methyl-sulfonyl-4-phenyl-2-butanone

(1) A solution of 3-phenylpropionic acid (50 g, 0.33 mole) and conc.sulfuric acid (5 g) in methanol (220 ml) was refluxed for 1 hour withstirring, concentrated and poured into cold H₂ O. The mixture wasextracted thrice with methylene chloride (75 ml), the organic layer waswashed thrice with H₂ O (125 ml), dried over anhydrous MgSO₄ andevaporated. The residual crude oil (54 g) was distilled under reducedpressure to give 51.5 g of methyl 3-phenylpropionate as a colorless oilhaving a boiling point of 94°-95° C.B 5 mmHg.

IR(Neat) ν cm⁻¹ : 1745 (CO₂).

(2) To a solution of dimethylsulfone (42 g, 0.45 mole) indimethylsulfoxide (225 ml), 60% sodium hydride (17.9 g, 0.45 mole) wasadded in a small portion at 18°-20° C., stirring was continued at65°-70° C. for 30 minutes, and then diluted with tetrahydrofuran (225ml). Then to this mixture, a solution of methyl 3-phenylpropionate (36.6g, 0.22 mole) obtained in above (1) in tetrahydro-furan (110 ml) wasadded dropwise at 33°-41° C., and reacted with stirring for 1 hour.After cooling, the reaction mixture was poured into diluted hydrochloricacid, and extracted 5 times with chloroform (100 ml). The organic layerwas washed thrice with H₂ O (200 ml), saturated aqueous sodiumbicarbonate (200 ml), then H₂ O (200 ml), dried over anhydrous MgSO₄ andevaporated. The crude solid (60.8 g) was recrystallized from ethylacetate to afford 24.7 g of 1-methylsulfonyl-4-phenylbutan-2-one aswhite needles having a melting point of 97.6-°98.4° C.

¹ HNMR δ ppm (CDCl₃): 2.91-3.09 (7H, m, C H₂ ×2 and C H₃), 3.99 (2H, s,C H₂), 7.16-7.33 (5H, m, Aromatic).

IR(KBr-disk) ν cm⁻¹ : 1730 ((C═O), 1320, 1305.

(3) To a solution of 1-methylsulfonyl-4-phenyl-butan-2-one (12 g, 0.05mole) obtained in above (2) in methylene chloride (135 ml),triethylamine (11.5 g) was added dropwise, and stirring was continuedfor 30 minutes. To this solution, p-toluenesulfonyl azide (11.5 g, 0.06mole) obtained in Reference Example 7, (1) was added dropwise at 0°-5°C., followed by reaction at the same temperature for 5 hours and thesolvent was removed. The residual solid (26.6 g) was recrystallized fromcarbon tetrachloride to give 7.5 g of1-diazo-1-methyl-sulfonyl-4-phenyl-2-butanone as pale yellow needleshaving a melting point of 52.5°-54° C.

¹ HNMR δ ppm (CDCl₃): 2.88-3.07 (4H, m, C H₂ ×2), 3.17 (3H, s, C H₃),7.16-7.35 (5H, m, Aromatic).

IR(KBr-disk) ν cm⁻¹ : 2120 (CN₂), 1655 (C═O), 1335, 1315.

REFERENCE EXAMPLE 12 Synthesis of1-diazo-1-(p-toluenesulfonyl)-3,3-dimethyl-2-butanone

(1) To a solution of 1-bromo-3,3-dimethyl-2-butanone (33.3 g, 0.19 mole)in dimethylsulfoxide (330 ml), sodium p-toluenesulfinate (34.9 g, 0.20mole) was added at 30°-40° C., and reacted with stirring at 60°-70° C.for 18 hours. The reaction mixture was poured into cold H₂ O (2 liter).The precipitate was filtered, washed with H₂ O and dried to afford 41.6g of 1-(p-toluene-sulfonyl)-3,3-dimethyl-2-butanone as white crystals.m.p. 119°-122° C.

¹ HNMR δ ppm (CDCl₃): 1.12 (9H, s, C H₃ ×3), 2.45 (3H, s, C H₃), 4.31(2H, s, C H₂), 7.36 (2H, d, J=8 Hz, Aromatic 3-H, 5-H), 7.82 (2H, d, J=8Hz, Aromatic 2-H, 6-H).

IR(KBr-disk) ν cm⁻¹ : 1715 (C═O), 1320, 1290.

(2) Using 1-(p-toluenesulfonyl)-3,3-dimethyl-2-butanone (20 g, 0.08mole) obtained in above (1), the reaction and treatment were carried outin the same manner as described in Reference Example 7, (3). Theresultant crude solid (24 g) was recrystallized from ethanol to give12.6 g of 1-diazo-1-(p-toluenesulfonyl)-3,3-dimethyl-2-butanone as paleyellow microneedles, m.p. 120.5°-121.5° C.

¹ HNMR δ ppm (CDCl₃): 1.17 (9H, s, C H₃ ×3), 2.44 (3H, s, C H₃), 7.34(2H, d, J=8 Hz, Aromatic 3-H, 5-H), 7.93 (2H, d, J=8 Hz, Aromatic 2-H,6-H).

REFERENCE EXAMPLE 13 Synthesis of1-acetyl-1-(1-methylethylsulfonyl)diazomethane

(1) To 2-propanethiol (12.2 g, 0.16 mole), a solution of potassiumhydroxide (11.5 g, 0.174 mole) in ethanol (100 ml) was added dropwise at15° C. or lower, and continued to stir at the same temperature for 24hours. Then chloroacetone (23.1 g, 0.25 mole) was added dropwise at10°-15° C., and reacted with stirring at 20° C. for 4 hours. To thismixture, sodium tungstate (0.8 g) was added, 30% hydrogen peroxide (36g, 0.32 mole) was added dropwise at 45°-55° C., and reacted withstirring at room temperature for 14 hours. The reaction mixture wasextracted with methylene chloride (200 ml). The organic layer was washedwith H₂ O, dried over anhydrous MgSO₄ and evaporated to give 18.9 g ofresidual crude 1-(1-methylethylsulfonyl) acetone as a brownish yellowoil.

¹ HNMR δ ppm (CDCl₃): 1.40 (6H, d, J=7 Hz, C H₃ ×2),2.40 (3H, s, C H₃),3.30 (1H, m, C H), 4.00 (2H, s, C H₂).

IR(Neat) ν cm⁻¹ : 1310, 1110.

(2) To a solution of crude 1-(1-methylethyl-sulfonyl)acetone (8.65 g,0.053 mole) obtained in above (1) and triethylamine (6.14 g, 0.061 mole)in ethanol (40 ml), p-toluenesulfonylazide (11.4 g, 0.058 mole) obtainedin Reference Example 7, (1) was added dropwise at 0°-5° C., followed byreaction at 10°-20° C. for 5 hours. After standing at room temperatureovernight, the solvent was removed. The residue was diluted withmethylene chloride (200 ml). The organic layer was washed with 5%potassium hydroxide aqueous solution (200 ml×1) and H₂ O (200 ml×3), andthen evaporated. The residue (12.4 g) was chromatographed on silica gel(Wakogel C-200, manufactured by Wako Pure Chemical Industries, Ltd.)with n-hexaneethylene chloride (4/1→1/1) as eluent, and then wasrecrystallized from n-hexane/ethanol to give 2.6 g of1-acetyl-1-(1-methylethylsulfonyl)diazomethane as pale yellowmicroneedles having a melting point of 53.0°-55.0° C.

¹ HNMR δ ppm (CDCl₃): 1.44 (6H, d, J=7 Hz, C H₃ ×2), 2.39 (3H, m, C H₃),3.51 (1H, m, C H).

IR(KBr-disk) ν cm⁻¹ : 2140 (CN₂), 1330 (SO₂), 1140.

REFERENCE EXAMPLE 14 Synthesis of 2,6-dinitrobenzyl p-toluenesulfonate

(1) To a suspension of 2,6-dinitrobenzaldehyde (19.6 g, 0.1 mole) inmethanol (200 ml), sodium boro-hydride (5.8 g) was added in a smallportion at 15°-25° C. The resultant mixture was stirred at roomtemperature for 1 hour and then concentrated. To the residue, H₂ O (100ml) and chloroform (100 ml) were added, followed by stirring for 1 hour.The chloroform layer was separated, washed with H₂ O, dried overanhydrous MgSO₄ and evaporated to afford 15.0 g of 2,6-dinitrobenzylalcohol as yellow crystals, m.p. 92.5°-93.5° C.

¹ HNMR δ ppm (CDCl₃): 2.77 (1H, t, J=7 Hz, OH), 4.97 (2H, d, J=7 Hz, CH₂), 7.66 (1H, t, J=8 Hz, Aromatic 4-H), 8.08 (2H, t, J=8 Hz, Aromatic3-H, 5-H).

(2) To a solution of 2,6-dinitrobenzyl alcohol (14.9 g, 0.075 mole)obtained in above (1) and p-toluenesulfonyl chloride (15.7 g, 0.083mole) in acetone (150 ml), a solution of dicyclohexylamine (15 g) inacetone (25 ml) was added dropwise at 0°-10° C., and stirring wascontinued for 4 hours at room temperature. The precipitate was filteredoff and the filtrate was evaporated. The residue (29 g) wasrecrystallized from carbon tetracloride to give 19.8 g of2,6-dinitrobenzyl p-toluenesulfonate as pale yellow leaflets having amelting point of 98°-99° C.

¹ HNMR δ (CDCl₃): 2.45 (3H, s, C H₃), 5.57 (2H, s, C H₂), 7.34 (2H, d,J=8 Hz, p-Tolyl 3-H, 5-H), 7.68 (1H, t, J=8 Hz, 2,6-dinitrophenyl 4-H),7.72 (2H, d, J=8 Hz, p-Tolyl 2-H, 6-H), 8.06 (2H, d, J=8 Hz,2,6-dinitrophenyl 3-H, 5-H).

IR(KBr-disk) ν cm⁻¹ : 1360, 1170.

REFERENCE EXAMPLE 15 Synthesis of cyclohexyl1-diazo-2-benzenesulfonylacetate

(1) To a solution of cyclohexyl bromoacetate (15.6 g, 0.0705 mole) indimethylsulfoxide (120 ml), sodium benzenesulfinate dihydrate (15 g,0.075 mole) was added in a small portion at 20°-40° C., and reacted withstirring at 60° C. for 6 hours. After cooling, the reaction mixture waspoured into cold H₂ O (1.5 liter). The precipitate was filtered, washedwith H₂ O and dried to give 15.3 g of cyclohexyl benzenesulfonylacetateas a white crystals having a melting point of 35°-38° C.

¹ HNMR δ ppm (CDCl₃): 1.11-1.82 (10H, m, cyclohexylic C H₂ ×5), 4.11(2H, s, C H₂), 4.64-4.82 (1H, m, C H), 7.50-7.98 (5H, m, Aromatic).

IR(KBr-disk) ν cm⁻¹ : 1735 (C═O), 1325 (SO₂), 1295.

(2) To a solution of cyclohexyl benzenesulfonyl-acetate (10 g, 0.035mole) obtained in above (1) in methylene chloride (100 ml),triethylamine (4.2 g, 0.041 mole) was added dropwise and continued tostir for 30 minutes. To this mixture, p-toluenesulfonylazide (8.3 g,0.039 mole) obtained in Reference Example 7, (1) was added dropwise at0°-5° C., reacted with stirring at the same temperature for 4 hours andconcentrated. The residue was diluted with ethyl ether (250 ml). Theorganic layer was washed with 5% potassium aqueous solution (200 ml×1)and brine (100 ml×1), dried over anhydrous MgSO₄ and evaporated. Theresidue (11 g) was purified by column chromatography on silica gel(Wakogel C-200) with n-hexaneethylene chloride (6/1→4/1→2/1→1/1) aseluent to give 5.6 g of cyclohexyl 2-diazo-2-benzenesulfonyl acetate aspale yellow crystals having a melting point of 42.0°-45.0° C.

¹ HNMR δ ppm (CDCl₃): 1.11-1.87 (10H, m, cyclohexylic C H₂ ×5),4.02-4.90 (1H, m, cyclohexylic C H), 7.47-8.07 (5H, m, Aromatic).

IR(Neat) ν cm⁻¹ : 2160 (CN₂), 1730 (C═O), 1365 (SO₂), 1310.

EXAMPLE 1

Each of the poly p-(1-ethoxyethyoxy)styrene-hydroxystyrene!s obtained inSynthesis Example 1 and Synthesis Example 4 was made into a solutionhaving the following composition:

Poly p-(1-ethoxyethoxy)styrene/p-hydroxystyrene!3.0 g

Diethylene glycol dimethyl ether 7.0g

Each of the compositions thus obtained was spin-coated on a substrate (aquartz wafer) and pre-baked on a hot plate at 90° C. for 90 seconds toobtain a polymer film of 1 μm in thickness. Then, each of the polymnerfilms thus obtained was subjected to UV measurement. Their UV spectraare shown in FIG. 1. In FIG. 1, I shows an ultravioletspectrophotometric curve of the polymer film obtained by use of thepolymer obtained in Synthesis Example 1, and II shows an ultravioletspectrophotometric curve of the polymer film obtained by use of thepolymer obtained in Synthesis Example 4. From the results shown in FIG.1, it can be seen that the polymer obtained in Synthesis Example 1 issuperior (more transparent) to the polymer obtained in Synthesis Example4 in light-transmitting properties particularly at approximately 240-250nm which is the same as or near the wavelength of KrF excimer laserbeams.

EXAMPLE 2

A photoresist composition was prepared according to the following recipeand a pattern was formed in the manner described below:

Poly p-(1-ethoxyethoxy)styrene/p-hydroxystyrene! (the polymer ofSynthesis Example 1) 6.0 g

2-(Cyclohexylcarbonyl)-2-(p-toluenesulfonyl)propane (the photoacidgenerator of Reference Example 4) 0.3 g

Diethylene glycol dimethyl ether 13.7 g

A pattern formation process using the above photoresist composition isexplained below with reference to FIG. 2. The photoresist composition 2was spin-coated on a semiconductor substrate 1 and pre-baked on a hotplate at 90° C. for 90 seconds to obtain a photoresist composition filmof 1.0 μm in thickness (FIG. 2(a)). Then, the film was selectivelyexposed to KrF excimer laser beams 3 having a wavelength of 248.4 nmthrough a mask 4 (FIG. 2(b)). After post-baking on a hot plate at 100°C. for 90 seconds, the film was developed with an alkali developingsolution (a 2.38% aqueous tetramethylammonium hydroxide solution) for 60seconds to dissolve away only the exposed portion of the photoresistcomposition 2, whereby a positive pattern 2a was obtained (FIG. 2(c)).

The positive pattern obtained showed a resolution of 0.25 μmline-and-space. In this case, the exposure dose was about 5 mJ/cm².

When a pattern change with a delay time between exposure and postexposure bake was measured using said photoresist composition, 0.25 μmline-and-space could be resolved without any trouble even after thelapse of 8 hours.

EXAMPLES 3 to 30

Photoresist compositions were prepared according to the respectiverecipes shown in Table 1.

                  TABLE 1                                                         ______________________________________                                        Example                                                                       No.      Photoresist composition                                              ______________________________________                                         3       Poly p-(1-ethoxyethoxy)styrene/                                                                      6.0 g                                                  p-hydroxystyrene! (Polymer of                                                 Synthesis Example 3)                                                          2-(Cyclohexylcarbonyl)-2-(p-                                                                         0.3 g                                                  toluenesulfonyl)propane                                                       (Photoacid generator of                                                       Reference Example 4)                                                          Diethylene glycol dimethyl ether                                                                     13.7 g                                         4       Poly p-(1-methoxy-1-methoxyethoxy)-                                                                  6.0 g                                                  styrene/p-hydroxystyrene                                                      (Polymer of Synthesis Example 7)                                              2-(Cyclohexylcarbonyl)-2-(p-                                                                         0.3 g                                                  toluenesulfonyl)propane                                                       (Photoacid generator of                                                       Reference Example 4)                                                          Diethylene glycol dimethyl ether                                                                     13.7 g                                         5       Poly p-(1-methoxyethoxy)styrene/                                                                     6.0 g                                                  p-hydroxystyrene! (Polymer of                                                 Synthesis Example 6)                                                          2-(Cyclohexylcarbonyl)-2-(p-                                                                         0.3 g                                                  toluenesulfonyl)propane                                                       (Photoacid generator of                                                       Reference Example 4)                                                          Diethylene glycol dimethyl ether                                                                     13.7 g                                         6       Poly p-(1-n-butoxyethoxy)styrene/                                                                    6.0 g                                                  p-hydroxystyrene! (Polymer of                                                 Synthesis Example 8)                                                          2-(Cyclohexylcarbonyl)-2-(p-                                                                         0.3 g                                                  toluenesulfonyl)propane                                                       (photoacid generator of                                                       Reference Example 4)                                                          Diethylene glycol dimethyl ether                                                                     13.7 g                                         7       Poly p-(1-lethoxyethoxy)styrene/                                                                     6.0 g                                                  p-hydroxystyrene! (Polymer of                                                 Synthesis Example 3)                                                          Bis(cyclohexylsulfonyl)-                                                                             0.4 g                                                  diazomethane (Photoacid generator                                             of Reference Example 7)                                                       Diethylene glycol dimethyl ether                                                                     13.6 g                                         8       Poly p-(1-ethoxyethoxy)styrene/p-                                                                    6.0 g                                                  hydroxystyrene! (Polymer of                                                   Synthesis Example 3)                                                          2,6-Dinitrobenzyl p-toluenesulfonate                                                                 0.3 g                                                  (Photoacid generator of                                                       Reference Example 14)                                                         Diethylene glycol dimethyl ether                                                                     13.7 g                                         9       Poly p-(1-methoxy-1-methylethoxy)-                                                                   6.0 g                                                  styrene/p-hydroxystyrene!                                                     (Polymer of Synthesis Example 7)                                              Bis(1,1-dimethylethylsulfonyl)-                                                                      0.3 g                                                  diazomethane (Photoacid generator                                             of Reference Example 9)                                                       Diethylene glycol dimethyl ether                                                                     13.7 g                                        10       Poly p-(1-ethoxyethoxy)styrene/p-                                                                    6.0 g                                                  hydroxystyrene! (Polymer of                                                   Synthesis Example 3)                                                          2-Methyl-2-(p-toluenesulfonyl)-                                                                      0.5 g                                                  propiophenone (Photoacid                                                      generator of Reference Example 5)                                             Diethylene glycol dimethyl ether                                                                     13.5 g                                        11       Poly p-(1-ethoxyethoxy)styrene/                                                                      6.0 g                                                  p-hydroxystyrene! (Polymer of                                                 Synthesis Example 5)                                                          Bis(cyclohexylsulfonyl)diazomethane                                                                  0.3 g                                                  (Photoacid generator of                                                       Reference Example 7)                                                          Diethylene glycol dimethyl ether                                                                     13.7 g                                        12       Poly p-(1-ethoxyethoxy)styrene/p-                                                                    6.0 g                                                  hydroxystyrene/fumaronitrile!                                                 (Polymer of Synthesis Example 9)                                              2,4-Dimethy1-2-(p-toluenesulfonyl)-                                                                  0.3 g                                                  pentan-3-one (Photoacid generator of                                          Reference Exmple 6)                                                           Diethylene glycol dimethyl ether                                                                     13.7 g                                        13       Poly p-(1-ethoxyethoxy)styrene/p-                                                                    6.0 g                                                  styrene! (Polymer of                                                          is Example 4)                                                                 Bis(cyclohexylsulfonyl)-                                                                             0.3 g                                                  diazomethane (Photoacid generator                                             of Reference Example 7)                                                       Diethylene glycol dimethyl ether                                                                     13.7 g                                        14       Poly p-(1-ethoxyethoxy)styrene/p-                                                                    6.0 g                                                  hydroxystyrene! (Polymer of                                                   Synthesis Example 1)                                                          Bis(cyclohexylsulfonyl)-                                                                             0.4 g                                                  diazomethane (Photoacid generator                                             of Reference Example 7)                                                       Diethylene glycol dimethyl ether                                                                     13.6 g                                        15       Poly p-(1-ethoxyethoxy)styrene/p-                                                                    6.0 g                                                  hydroxystyrene! (Polymer of                                                   Synthesis Example 4)                                                          2-(Cyclohexylcarbonyl)-2-                                                                            0.3 g                                                  (p-toluenesulfonyl)propane                                                    (Photoacid generator of Reference                                             Example 4)                                                                    Diethylene glycol dimethyl ether                                                                     13.7 g                                        16       Poly p-(1-ethoxyethoxy)styrene/p-                                                                    6.0 g                                                  hydroxystyrene! (Polymer of                                                   Synthesis Example 1)                                                          2-Methy1-2-(p-toluenesulfonyl)-                                                                      0.3 g                                                  propiophenone (Photoacid generator                                            of Reference Example 5)                                                       Diethylene glycol dimethyl ether                                                                     13.7 g                                        17       Poly p-1-ethoxyethoxy)styrene/p-                                                                     6.0 g                                                  hydroxystyrene! (Polymer of                                                   Synthesis Example 5)                                                          Bis(1,1-dimethylethylsulfonyl)-                                                                      0.3 g                                                  diazomethane (Photoacid generator                                             of Reference Example 9)                                                       Diethylene glycol dimethyl ether                                                                     13.7 g                                        18       Poly p-(1-ethoxyethoxy)styrene/p-                                                                    6.0 g                                                  hydroxystyrene/tert-butyl                                                     methacrylate! (Polymer of                                                     Synthesis Example 10)                                                         Methylsulfonyl p-toluenesulfonyl-                                                                    0.3 g                                                  diazomethane (Photoacid generator                                             of Reference Example 8)                                                       Diethylene glycol dimethyl ether                                                                     13.7 g                                        19       Poly p-(1-ethoxyethoxy)styrene/                                                                      6.0 g                                                  p-hydroxyethylene/tert-butyl                                                  methacrylate! (Polymer of                                                     Synthesis Example 10)                                                         1-Diazo-1-cyclohexylsulfonyl-                                                                        0.3 g                                                  3,3-dimethy1-2-butanone                                                       (Photoacid generator of                                                       Reference Example 10)                                                         Diethylene glycol dimethyl ether                                                                     13.7 g                                        20       Poly p-(1-methoxyethoxy)styrene/                                                                     6.0 g                                                  p-hydroxystyrene! (Polymer of                                                 Synthesis Example 6)                                                          1-Diazo-1-methylsulfony1-4-                                                                          0.3 g                                                  phenyl-2-butanone (Photoacid                                                  generator of Reference Example 11)                                            Ethyl lactate          13.7 g                                        21       Poly p-(1-ethoxyethoxy)styrene/                                                                      6.0 g                                                  p-hydroxystyrene! (Polymer of                                                 Synthesis Example 2)                                                          Bis(cyclohexylsulfonyl)diazo-                                                                        0.4 g                                                  methane (Photoacid generator                                                  of Reference Example 7)                                                       Diethylene glycol dimethyl ether                                                                     13.6 g                                        22       Poly p-(1-methoxy-1-methyethoxy)-                                                                    6.0 g                                                  styrene/p-hydroxystyrene)                                                     (Polymer of Synthesis Example 7)                                              Bis(cyclohexylsulfonyl)-                                                                             0.3 g                                                  diazomethane (Photoacid generator                                             of Reference Example 7)                                                       Diethylene glycol dimethyl ether                                                                     13.7 g                                        23       Poly p-(1-ethoxyethoxy)styrene/                                                                      6.0 g                                                  p-hydroxystyrene! (Polymer of                                                 Synthesis Example 3)                                                          1-Diazo-1-(p-toluenesulfonyl)-3,3-                                                                   0.3 g                                                  dimethyl-2-butanone (Photoacid                                                generator of Reference Example 12)                                            Propylene glycol monomethyl ether                                                                    13.7 g                                                 acetate                                                              24       Poly p-(1-ethoxyethoxy)styrene/                                                                      6.0 g                                                  p-hydroxystyrene! (Polymer                                                    of Synthesis Example 5)                                                       1-Diazo-1-(1,1-dimethylethyl-                                                                        0.4 g                                                  sulfonyl)-3,3-dimethyl-2-                                                     butanone (Photoacid generator                                                 of Reference Example 12)                                                      Methyl 3-methoxypropionate                                                                           13.6 g                                        25       Poly p-(1-ethoxyethoxy)styrene/                                                                      6.0 g                                                  p-hydroxystyrene! (Polymer of                                                 Synthesis Example 3)                                                          2-(Cyclohexylcarbonyl)-                                                                              0.3 g                                                  (p-toluenesulfonyl)propane                                                    (Photoacid generator of                                                       Reference Example 4)                                                          Ethyl lactate          13.7 g                                        26       Poly p-(1-methoxy-1-methyethoxy) -                                                                   5.5 g                                                  styrene/p-hydroxystyrene! (Polymer                                            Synthesis Exmaple 7)                                                          1-Acetyl-1-(1-methylethyl-                                                                           0.2 g                                                  sulfonyl)diazomethane                                                         (Photoacid generator of Reference                                             Example 13)                                                                   Propylene glycol monomethyl                                                                          14.3 g                                                 ether acetate                                                        27       Poly p-(1-n-butoxyethoxy)-                                                                           6.0 g                                                  styrene/p-hydroxystyrene!                                                     (Polymer of Synthesis Example 8)                                              Bis(cyclohexylsulfonyl)-                                                                             0.3 g                                                  methane (Photoacid generator                                                  Reference Example 7)                                                          Diethylene glycol dimethyl ether                                                                     13.7 g                                        28       Poly p-(1-methoxyethoxy)styrene/                                                                     5.8 g                                                  p-hydroxystyrene! (Polymer of                                                 Synthesis Example 6)                                                          Cyclohexyl 2-diazo-2-  0.2 g                                                  benzenesulfonylacetate                                                        (Photoacid generator of                                                       Reference Example 15)                                                         Diethylene glycol dimethyl ether                                                                     14.0 g                                        29       Poly p-(1-ethoxyethoxy)styrene/                                                                      6.0 g                                                  p-hydroxystyrene/tert-butyl                                                   methacrylate! (polymer of                                                     Synthesis Example 10)                                                         2,6-Dinitrobenzyl p-toluene-                                                                         0.1 g                                                  sulfonate (photoacid generator                                                of Reference Example 14)                                                      Ethyl lactate          13.9 g                                        30       Poly p-1-ethoxyethoxy)styrene/                                                                       6.0 g                                                  p-hydroxystyrene/fumaronitrile!                                               (Polymer of Synthesis Example 9)                                              1-Acetyl-1-(1-methylethylsulfonyl)-                                                                  0.3 g                                                  diazomethane (Photoacid generator                                             of Reference Example 13)                                                      Diethylene glycol dimethyl ether                                                                     13.6 g                                        ______________________________________                                    

Pattern formation was carried out in the same manner as in Example 2except for using each photoresist composition prepared in the above. Theresults obtained are shown in Table 2.

                  TABLE 2                                                         ______________________________________                                                Exposure Interval between exposure and heat                           Example dose     treatment, and resolution                                    No.     (mJ/cm.sup.2)                                                                          At once    30 min  8 hrs                                     ______________________________________                                         3      15       0.30 μm L/S                                                                           0.30 μm L/S                                                                        0.30 μm L/S                             4      20       0.30 μm L/S                                                                           0.30 μm L/S                                                                        0.30 μm L/S                             5       8       0.25 μm L/S                                                                           0.25 μm L/S                                                                        0.25 μm L/S                             6      15       0.30 μm L/S                                                                           0.30 μm L/S                                                                        0.30 μm L/S                             7      15       0.30 μm L/S                                                                           0.30 μm L/S                                                                        0.30 μm L/S                             8       8       0.30 μm L/S                                                                           0.30 μm L/S                                                                        0.30 μm L/S                             9      16       0.22 μm L/S                                                                           0.22 μm L/S                                                                        0.22 μm L/S                            10       8       0.30 μm L/S                                                                           0.30 μm L/S                                                                        0.30 μm L/S                            11      18       0.22 μm L/S                                                                           0.22 μm L/S                                                                        0.22 μm L/S                            12      16       0.30 μm L/S                                                                           0.30 μm L/S                                                                        0.30 μm L/S                            13      15       0.30 μm L/S                                                                           0.30 μm L/S                                                                        0.30 μm L/S                            14      15       0.22 μm L/S                                                                           0.22 μm L/S                                                                        0.22 μm L/S                            15      15       0.30 μm L/S                                                                           0.30 μm L/S                                                                        0.30 μm L/S                            16      12       0.22 μm L/S                                                                           0.22 μm L/S                                                                        0.22 μm L/S                            17      18       0.22 μm L/S                                                                           0.22 μm L/S                                                                        0.22 μm L/S                            18      10       0.30 μm L/S                                                                           0.30 μm L/S                                                                        0.30 μm L/S                            19      20       0.30 μm L/S                                                                           0.30 μm L/S                                                                        0.30 μm L/S                            20      12       0.25 μm L/S                                                                           0.25 μm L/S                                                                        0.25 μm L/S                            21      16       0.30 μm L/S                                                                           0.30 μm L/S                                                                        0.30 μm L/S                            22      12       0.22 μm L/S                                                                           0.22 μm L/S                                                                        0.22 μm L/S                            23      15       0.30 μm L/S                                                                           0.30 μm L/S                                                                        0.30 μm L/S                            24      12       0.22 μm L/S                                                                           0.22 μm L/S                                                                        0.22 μm L/S                            25      10       0.25 μm L/S                                                                           0.25 μm L/S                                                                        0.25 μm L/S                            26      15       0.25 μm L/S                                                                           0.25 μm L/S                                                                        0.25 μm L/S                            27      18       0.25 μm L/S                                                                           0.25 μm L/S                                                                        0.25 μm L/S                            28      18       0.25 μm L/S                                                                           0.25 μm L/S                                                                        0.25 μm L/S                            29       8       0.30 μm L/S                                                                           0.30 μm L/S                                                                        0.30 μm L/S                            30      18       0.30 μm L/S                                                                           0.30 μm L/S                                                                        0.30 μm L/S                            ______________________________________                                    

As is clear from Table 2, in any of Examples 3 to 30, a positive patterncould be formed as in Example 2, and 0.22 to 0.3 μm line-and-space couldbe resolved without any trouble even after the lapse of 8 hours betweenexposure and post exposure bake, as in Example 2.

COMPARATIVE EXAMPLES 1 to 9

For comparison, photoresist compositions were prepared according to therespective recipes shown in Table 3, and pattern formation was carriedout in the same manner as described in Example 2 except for using eachof said photoresist compositions. The results obtained are shown inTable 4. FIG. 3 shows a pattern result ("T-shaped" profile: T-shape)obtained in Comparative Example 1 when post exposure bake and then thedevelopment were carried out after the lapse of 30 minutes after theexposure. FIG. 4 shows a pattern result (the impossibility of patternformation) obtained in Comparative Examples 2 and 3 when the heattreatment and then the development were carried out after the lapse of30 minutes after the exposure, and that obtained in Comparative Examples4 to 6 and 9 when the heat treatment and then the development werecarried out after the lapse of 15 minutes after the exposure.

Further, in Comparative Examples 7 and 8, wherein the heat treatment anddevelopment were carried out after exposure to light, no pattern wasformed at all, since both the exposed portions and non-exposed portionswere dissolved.

                  TABLE 3                                                         ______________________________________                                        Comparative                                                                   Example No.                                                                             Photoresist composition                                             ______________________________________                                        1         Poly(p-tetrahydropyranyloxystyrene/                                                                6.0 g                                                    p-hydroxystyrene (Polymer of                                                  Reference Example 1)                                                          2-(Cyclohexylcarbonyl)-2-(p-                                                                       0.3 g                                                    toluenesulfonyl)propane                                                       (Photoacid generator of                                                       Reference Example 4)                                                          Diethylene glycol dimethyl ether                                                                   13.7 g                                         2         Poly(p-tert-butoxystyrene/                                                                         6.0 g                                                    p-hydroxystyrene) (Polymer of                                                 Reference Example 2)                                                          2-(Cyclohexylcarbonyl)-2-(p-                                                                       0.3 g                                                    toluenesulfonyl)propane                                                       (Photoacid generator of                                                       Reference Example 4)                                                          Diethylene glycol dimethyl ether                                                                   13.7 g                                         3         Poly(p-tert-butoxycarbonyloxy-                                                                     6.0 g                                                    styrene/p-hydroxystyrene)                                                     Polymer of Reference Example 3)                                               2-(Cyclohexylcarbonyl)-2-(p-                                                                       0.3 g                                                    toluenesulfonyl)propane                                                       (Photoacid generator of                                                       Reference Example 4)                                                          Diethylene glycol dimethyl ether                                                                   13.7 g                                         4         Poly(p-tertrahydropyranyloxy-                                                                      6.0 g                                                    styrene/p-hydroxystyrene)                                                     (Polymer of Reference Example 1)                                              Diphenyliodonium hexafluoro-                                                                       0.3 g                                                    phosphate                                                                     Diethylene glycol dimethyl ether                                                                   13.7 g                                         5         Poly(p-tert-butoxystyrene/p-                                                                       6.0 g                                                    hydroxystyrene) (Polymer of                                                   Reference Example 2)                                                          Diphenyliodonium hexafluoro-                                                                       0.3 g                                                    phosphate                                                                     Diethylene glycol dimethyl ether                                                                   13.7 g                                         6         Poly(p-tert-butoxycarbonyloxy-                                                                     6.0 g                                                    styrene/p-hydroxystyrene)                                                     (Polymer of Reference Example 3)                                              Diphenyliodonium hexafluoro-                                                                       0.3 g                                                    phosphate                                                                     Diethylene glycol dimethyl ether                                                                   13.7 g                                         7         Poly p-(1-ethoxyethoxy)styrene/                                                                    6.0 g                                                    p-hydroxystyrene! (Polymer of                                                 Synthesis Example 1)                                                          Diphenyliodonium hexalfuoro-                                                                       0.3 g                                                    phosphate                                                                     Diethylene glycol dimethyl                                                                         13.7 g                                                   ether                                                               8         Poly p-(1-ethoxyethoxy)styrene/                                                                    6.0 g                                                    p-hydroxystyrene! (Polymer of                                                 Synthesis Example 1)                                                          Triphenylsulfonium hexa-                                                                           0.3 g                                                    fluorophosphate                                                               Diethylene glycol dimethyl ether                                                                   13.7 g                                         9         Poly p-(1-ethoxyethoxy)styrene/                                                                    6.0 g                                                    p-hydroxystyrene! (Polymer of                                                 Synthesis Example 1)                                                          Tris(tirchloromethyl)-s-triazine                                                                   1.1 g                                                    Triethanolamine      0.1 g                                                    Diethylene glycol dimethyl ether                                                                   12.8 g                                         ______________________________________                                    

                                      TABLE 4                                     __________________________________________________________________________    Comparative                                                                         Exposure                                                                           Interval between exposure and heat                                 Example                                                                             dose treatment, and resolution                                          No.   (mJ/cm.sup.2)                                                                      At once                                                                             15 min                                                                              3 min    1 hr                                          __________________________________________________________________________    1     30   0.35 μm L/S                                                                      0.35 μm L/S                                                                      "T-shaped" profile                                                                     No pattern                                                                    was formed.                                   2     30   0.35 μm L/S                                                                      0.35 μm L/S                                                                      No pattern was                                                                         --                                                                   formed.                                                3     35   0.35 μm L/S                                                                      0.35 μm L/S                                                                      No pattern was                                                                         --                                                                   formed.                                                4     3    0.35 μm L/S                                                                      No pattern                                                                          --       --                                                             was formed.                                                  5     3    0.35 μm L/S                                                                      No pattern                                                                          --       --                                                             was formed.                                                  6     3    0.35 μm L/S                                                                      No pattern                                                                          --       --                                                             was formed.                                                  7     3    No pattern                                                                          --    --       --                                                       was formed.                                                        8     3    No pattern                                                                          --    --       --                                                       was formed.                                                        9     6    0.40 μm L/S                                                                      --    --       --                                            __________________________________________________________________________

As is clear from Table 4, FIG. 3 and FIG. 4, all the photoresistcompositions prepared in Comparative Examples 1 to 9 are inferior inresolution to the photoresist compositions obtained by use of thestarting materials according to this invention. As is clear fromComparative Examples 1 to 6, when after the exposure, it is more than15-30 minutes before the heat treatment (the post-baking), "T-shaped"profile occurs, or pattern formation becomes impossible. As is clearfrom the results of Comparative Examples 7 and 8, the whole photoresistcompositions obtained by combining the polymer used in this inventionwith an existing iodonium salt or sulfonium salt as photoacid generatorwere dissolved by the development after the exposure, so that nopositive pattern was formed. In the case of Comparative Example 9,wherein the resist material comprising the polymer usable in the presentinvention and a known combination oftris(trichloromethyl)-s-triazine/proton doner as a photoacid generatorwas used, when a period of 15 to 30 minutes was required from the lightexposure to heat treatment, no pattern was formed.

As is clear from the above, when the photoresist composition of thisinvention is used as a resist material for exposure to light having awavelength of 300 nm or less, such as deep ultraviolet light (Deep UV),for example, KrF excimer laser beams (248.4 nm), there can easily beobtained a fine pattern which shows a very high resolution, permitsstable maintenance of the dimensions of the pattern during a time delaybetween exposure and post exposure bake, and has a good shape ofpractical quater micron order. Therefore, this invention is of greatvalue in formation of an ultra-fine pattern in the semiconductorindustry.

The photoresist compositions of this invention are effectiveparticularly in pattern formation using deep ultraviolet light or KrFexcimer laser beams. They are sufficiently usable also for patternformation using i-line light, electron beams, X-rays or the like.

What is claimed is:
 1. A process for forming a pattern whichcomprises(i) a step of coating a photoresist composition on a substrate,the photoresist composition comprising(a) a polymer having repeatingunits of the formula: ##STR20## wherein R¹ is a hydrogen atom or amethyl group; R² and R³ are independently a hydrogen atom, or a linear,branched or cyclic alkyl group having 1 to 6 carbon atoms provided thatR² and R³ cannot be hydrogen atoms at the same time, and a combinationof R² and R³ being able to form a methylene chain having 2 to 5 carbonatoms; R⁴ is a linear, branched or cyclic alkyl groups having 1 to 10carbon atoms, a linear, branched or cyclic haloalkyl group having 1 to 6carbon atoms, or an aralkyl group; R⁵ is a hydrogen atom or a cyanogroup; R⁷ is a hydrogen atom, a cyano group or--COOY; Y is a linear,branched or cyclic alkyl group having 1 to 6 carbon atoms; R⁵ and R⁷ maybind to each other to form --CO--O--CO; k and l are independently anatural number (0.1≦k/(k+l)≦0.5; and m is zero or a natural number (whenm is a natural number, 0.05≦m/(k+l+m)≦0.50), (b) a photosensitivecompound which generates an acid upon exposure to light and, (c) asolvent capable of dissolving the components (a) and (b); (ii) a step ofexposing the coating to light having a wavelength of 300 nm or lessthrough a mask after heat treatment, and (iii) a step of developing thecoating by use of a developing solution after carrying out heattreatment if necessary.
 2. A process according to claim 1, wherein thepolymer of the formula I! has repeating units of the formula: ##STR21##wherein R¹ is a hydrogen atom or a methyl group; R² and R³ areindependently a hydrogen atom, or a linear, branched or cyclic alkylgroup having 1 to 6 carbon atoms provided that R² and R³ cannot both behydrogen atoms, and a combination of R² and R³ being able to form amethylene chain having 2 to 5 carbon atoms; R⁴ is a linear, branched orcyclic alkyl group having 1 to 10 carbon atoms, atoms, or an aralkylgroup; and k and l are independently a natural number and(0.1≦k/(k+l)≦0.5.
 3. A process according to claim 1, wherein the polymerof the formula I! is a polymer in which R¹ is a hydrogen atom; R² is ahydrogen atom or a linear or branched alkyl group having 1 to 6 carbonatoms; R³ is a linear or branched alkyl group having 1 to 6 carbonatoms; and R⁴ is a linear or branched alkyl group having 1 to 10 carbonatoms.
 4. A process according to claim 1, wherein the polymer of theformula I! is a polymer in which R¹ is a hydrogen atom; R² is a hydrogenatom or a methyl group; R³ is a methyl group or an ethyl group; and R⁴is a linear or branched alkyl group having 1 to 4carbon atoms.
 5. Aprocess according to claim 1, wherein the weight average molecular ofthe polymer of the formula I! is 3,000 to 20,000.
 6. A process forforming a pattern which comprises(i) a step of coating a photoresistcomposition on a substrate, the photoresist composition comprising(a) apolymer having repeating units of the formula: ##STR22## wherein R¹ is ahydrogen atom or a methyl group; R² and R³ are independently a hydrogenatom, or a linear, branched or cyclic alkyl group having 1 to 6 carbonatoms provided that R² and R³ cannot be hydrogen atoms at the same time,and a combination of R² and R³ being able to form a methylene chainhaving 2 to 5 carbon atoms; R⁴ is a linear, branched or cyclic alkylgroups having 1 to 10 carbon atoms, a linear, branched or cyclichaloalkyl group having 1 to 6 carbon atoms, or an aralkyl group; R⁵ is ahydrogen atom or a cyano group; R⁷ is a hydrogen atom, a cyano groupor--COOY; Y is a linear, branched or cyclic alkyl group having 1 to 6carbon atoms; R⁵ and R⁷ may bind to each other to form --CO--O--CO; kand l are independently a natural number (0.1≦k/(k+l)≦0.5; and m is zeroor a natural number (when m is a natural number, 0.05≦m/(k+l+m)≦0.50),(b) a photosensitive compound which generates an acid upon exposure tolight and, (c) a solvent capable of dissolving the components (a) and(b); (ii) a step of irradiating the coating with electron beams througha mask after heat treatment, and (iii) a step of developing the coatingby use of a development solution after carrying out heat treatment orwithout heat treatment.
 7. A process according to claim 2, wherein thepolymer of the formula I! has repeating units of the formula: ##STR23##wherein R¹ is a hydrogen atom or a methyl group; R² and R³ areindependently a hydrogen atom, or a linear, branched or cyclic alkylgroup having 1 to 6 carbon atoms provided that R² and R³ cannot both behydrogen atoms, and a combination of R² and R³ being able to form amethylene chain having 2 to 5 carbon atoms; R⁴ is a linear, branched orcyclic alkyl group having 1 to 10 carbon atoms, a linear, branched orcyclic haloalkyl group having 1 to 6 carbon atoms, or an aralkyl group;and k and l are independently a natural number and (0.1≦k/(k+l)≦0.5. 8.A process according to claim 6, wherein the polymer of the formula I! isa polymer in which R¹ is a hydrogen atom; R² is a hydrogen atom or alinear or branched alkyl group having 1 to 6 carbon atoms; R³ is alinear or branched alkyl group having 1 to 6 carbon atoms; and R⁴ is alinear or branched alkyl group having 1 to 10 carbon atoms.
 9. A processaccording to claim 6, wherein the polymer of the formula I! is a polymerin which R¹ is a hydrogen atom; R² is a hydrogen atom or a methyl group;R³ is a methyl group or an ethyl group; and R⁴ is a linear or branchedalkyl group having 1 to 4 carbon atoms.
 10. A process according to claim6, wherein the weight average molecular of the polymer of the formula I!is 3,000 to 20,000.
 11. A process for forming a pattern whichcomprises(i) a step of coating a photoresist composition on a substrate,the photoresist composition comprising(a) a polymer having repeatingunits of the formula: ##STR24## wherein R¹ is a hydrogen atom or amethyl group; R² and R³ are independently a hydrogen atom, or a linear,branched or cyclic alkyl group having 1 to 6 carbon atoms provided thatR² and R³ cannot be hydrogen atoms at the same time, and a combinationof R² and R³ being able to form a methylene chain having 2 to 5 carbonatoms; R⁴ is a linear, branched or cyclic alkyl groups having 1 to 10carbon atoms, a linear, branched or cyclic haloalkyl group having 1 to 6carbon atoms, or an aralkyl group; R⁵ is a hydrogen atom or a cyanogroup; R⁷ is a hydrogen atom, a cyano group or--COOY; Y is a linear,branched or cyclic alkyl group having 1 to 6 carbon atoms; R⁵ and R⁷ maybind to each other to form --CO--O--CO; k and l are independently anatural number (0.1≦k/(k+l)≦0.9); and m is zero or a natural number(when m is a natural number, 0.05≦m/(k+l+m)≦0.50), (b) a photosensitivecompound which generates an acid upon exposure to light, thephotosensitive compound being a compound represented by the formula:##STR25## wherein R⁸ are R⁹ independently a linear, branched or cyclicalkyl group having 1 to 10 carbon atoms, a haloalkyl group having 1 to10 carbon atoms, or a group represented by the formula: ##STR26##wherein R¹⁰ and R¹¹ are independently a hydrogen atom, a linear orbranched alkyl group having 1 to 5 carbon atoms, or a haloalkyl grouphaving 1 to 5 carbon atoms which may be either linear or branched; and nis zero or a natural number, and, (c) a solvent capable of dissolvingthe components (a) and (b); (ii) a step of exposing the coating to lighthaving a wavelength of 300 nm or less through a mask after heattreatment, and (iii) a step of developing the coating by use of adeveloping solution after carrying out heat treatment if necessary. 12.A process for forming a pattern which comprises(i) a step of coating aphotoresist composition on a substrate, the photoresist compositioncomprising(a) a polymer having repeating units of the formula: ##STR27##wherein R¹ is a hydrogen atom or a methyl group; R² and R³ areindependently a hydrogen atom, or a linear, branched or cyclic alkylgroup having 1 to 6 carbon atoms provided that R¹ and R³ cannot behydrogen atoms at the same time, and a combination of R² and R³ beingable to form a methylene chain having 2 to 5 carbon atoms; R⁴ is alinear, branched or cyclic alkyl groups having 1 to 10 carbon atoms, alinear, branched or cyclic haloalkyl group having 1 to 6 carbon atoms,or an aralkyl group; R⁵ is a hydrogen atom or a cyano group; ⁷ is ahydrogen atom, a cyano group or--COOY; Y is a linear, branched or cyclicalkyl group having 1 to 6 carbon atoms; R⁵ and R⁷ may bind to each otherto form --CO--O--CO; k and l are independently a natural number(0.1≦k/(k+l)≦0.9); and m is zero or a natural number (when m is anatural number, 0.05≦m/(k+l+m)≦0.50), (b) a photosensitive compoundwhich generates an acid upon exposure to light, the photosensitivecompound being a compound represented by the formula: ##STR28## whereinR¹² is a linear, branched or cyclic alkyl group having 1 to 10 carbonatoms, an aralkyl group, a trifluoromethyl group, a phenyl group or atolyl group; R¹³ and R¹⁴ are independently a hydrogen atom, or a linearor branched alkyl group having 1 to 5 carbon atoms; and R¹⁵ is a linear,branched or cyclic alkyl group having 1 to 10 carbon atoms, a phenylgroup, a halogen-substituted phenyl group, an alkyl-substituted phenylgroup, an alkoxy-substituted phenyl group, or an alkylthio-substitutedphenyl group, and, (c) a solvent capable of dissolving the components(a) and (b); (ii) a step of exposing the coating to light having awavelength of 300 mm or less through a mask after heat treatment, and(iii) a step of developing the coating by use of a developing solutionafter carrying out heat treatment if necessary.
 13. A process forforming a pattern which comprises(i) a step of coating a photoresistcomposition on a substrate, the photoresist composition comprising(a) apolymer having repeating units of the formula: ##STR29## wherein R¹ is ahydrogen atom or a methyl group; R² and R³ are independently a hydrogenatom, or a linear, branched or cyclic alkyl group having 1 to 6 carbonatoms provided that R² and R³ cannot be hydrogen atoms at the same time,and a combination of R² and R³ being able to form a methylene chainhaving 2 to 5 carbon atoms; R⁴ is a linear, branched or cyclic alkylgroups having 1 to 10 carbon atoms, a linear, branched or cyclichaloalkyl group having 1 to 6 carbon atoms, or an aralkyl group; R⁵ is ahydrogen atom or a cyano group; R⁷ is a hydrogen atom, a cyano groupor--COOY; Y is a linear, branched or cyclic alkyl group having 1 to 6carbon atoms; R⁵ and R⁷ may bind to each other to form --CO--O--CO; kand l are independently a natural number (0.1≦k/(k+l)≦0.9); and m iszero or a natural number (when m is a natural number,0.05≦m/(k+l+m)≦0.50), (b) a photosensitive compound which generates anacid upon exposure to light, the photosensitive compound being acompound represented by the formula: ##STR30## wherein R¹⁶ is a linear,branched or cyclic alkyl group having 1 to 10 carbon atoms, an aralkylgroup, a trifluoromethyl group, a phenyl group or a tolyl group; and R¹⁷is a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms,an aralkyl group or an alkoxy group, and, (c) a solvent capable ofdissolving the components (a) and (b); (ii) a step of exposing thecoating to light having a wavelength of 300 nm or less through a maskafter heat treatment, and (iii) a step of developing the coating by useof a developing solution after carrying out heat treatment if necessary.14. A process for forming a pattern which comprises(i) a step of coatinga photoresist composition on a substrate, the photoresist compositioncomprising(a) a polymer having repeating units of the formula: ##STR31##wherein R¹ is a hydrogen atom or a methyl group; R² and R³ areindependently a hydrogen atom, or a linear, branched or cyclic alkylgroup having 1 to 6 carbon atoms provided that R² and R³ cannot behydrogen atoms at the same time, and a combination of R² and R³ beingable to form a methylene chain having 2 to 5 carbon atoms; R⁴ is alinear, branched or cyclic alkyl groups having 1 to 10 carbon atoms, alinear, branched or cyclic haloalkyl group having 1 to 6 carbon atoms,or an aralkyl group; R⁵ is a hydrogen atom or a cyano group; R⁷ is ahydrogen atom, a cyano group or--COOY; Y is a linear, branched or cyclicalkyl group having 1 to 6 carbon atoms; R⁵ and R⁷ may bind to each otherto form --CO--O--CO; k and l are independently a natural number(0.1≦k/(k+l)≦0.9); and m is zero or a natural number (when m is anatural number, 0.05≦m/(k+l+m)≦0.50), (b) a photosensitive compoundwhich generates an acid upon exposure to light, the photosensitivecompound being a compound represented by the formula: ##STR32## whereinR¹⁸ is a trichloroacetyl group, a p-toluene-sulfonyl group, ap-trifluoromethylbenzenesulfonyl group, a methanesulfonyl group or atrifluoromethanesulfonyl group; and R¹⁹ and R²⁰ are independently ahydrogen atom, a halogen atom or a nitro group, and, (c) a solventcapable of dissolving the components (a) and (b); (ii) a step ofexposing the coating to light having a wavelength of 300 nm or lessthrough a mask after heat treatment, and (iii) a step of developing thecoating by use of a developing solution after carrying out heattreatment if necessary.
 15. A process for forming a pattern whichcomprises(i) a step of coating a photoresist composition on a substrate,the photoresist composition comprising(a) a polymer having repeatingunits of the formula: ##STR33## wherein R¹ is a hydrogen atom or amethyl group; R² and R³ are independently a hydrogen atom, or a linear,branched or cyclic alkyl group having 1 to 6 carbon atoms provided thatR² and R³ cannot be hydrogen atoms at the same time, and a combinationof R² and R³ being able to form a methylene chain having 2 to 5 carbonatoms; R⁴ is a linear, branched or cyclic alkyl groups having 1 to 10carbon atoms, a linear, branched or cyclic haloalkyl group having 1 to 6carbon atoms, or an aralkyl group; R⁵ is a hydrogen atom or a cyanogroup; R⁷ is a hydrogen atom, a cyano group or--COOY; Y is a linear,branched or cyclic alkyl group having 1 to 6 carbon atoms; R⁵ and R⁷ maybind to each other to form --CO--O--CO; k and l are independently anatural number (0.1≦k/(k+l)≦0.9); and m is zero or a natural number(when m is a natural number, 0.05≦m/(k+l+m)≦0.50), (b) a photosensitivecompound which generates an acid upon exposure to light, thephotosensitive compound being a compound represented by the formula:##STR34## wherein R⁸ and R⁹ are independently a linear, branched orcyclic alkyl group having 1 to 10 carbon atoms, a haloalkyl group having1 to 10 carbon atoms, or a group represented by the formula: ##STR35##wherein R¹⁰ and R¹¹ are independently a hydrogen atom, a linear orbranched alkyl group having 1 to 5 carbon atoms, or a haloalkyl grouphaving 1 to 5 carbon atoms which may be either linear or branched; and nis zero or a natural number, and, (c) a solvent capable of dissolvingthe components (a) and (b); (ii) a step of irradiating the coating withelectron beams through a mask after heat treatment, and (iii) a step ofdeveloping the coating by use of a development solution after carryingout heat treatment or without heat treatment.
 16. A process for forminga pattern which comprises(i) a step of coating a photoresist compositionon a substrate, the photoresist composition comprising(a) a polymerhaving repeating units of the formula: ##STR36## wherein R¹ is ahydrogen atom or a methyl group; R² and R³ are independently a hydrogenatom, or a linear, branched or cyclic alkyl group having 1 to 6 carbonatoms provided that R² and R³ cannot be hydrogen atoms at the same time,and a combination of R² and R³ being able to form a methylene chainhaving 2 to 5 carbon atoms; R⁴ is a linear, branched or cyclic alkylgroups having 1 to 10 carbon atoms, a linear, branched or cyclichaloalkyl group having 1 to 6 carbon atoms, or an aralkyl group; R⁵ is ahydrogen atom or a cyano group; R⁷ is a hydrogen atom, a cyano groupor--COOY; Y is a linear, branched or cyclic alkyl group having 1 to 6carbon atoms; R⁵ and R⁷ may bind to each other to form --CO--O--CO; kand l are independently a natural number (0.1≦k/(k+l)≦0.9); and m iszero or a natural number (when m is a natural number,0.05≦m/(k+l+m)≦0.50), (b) a photosensitive compound which generates anacid upon exposure to light, the photosensitive compound being acompound represented by the formula: ##STR37## wherein R¹² is a linear,branched or cyclic alkyl group having 1 to 10 carbon atoms, an aralkylgroup, a trifluoromethyl group, a phenyl group or a tolyl group; R¹³ andR¹⁴ are independently a hydrogen atom, or a linear or branched alkylgroup having 1 to 5 carbon atoms; and R¹⁵ is a linear, branched orcyclic alkyl group having 1 to 10 carbon atoms, a phenyl group, ahalogen-substituted phenyl group, an alkyl-substituted phenyl group, analkoxy-substituted phenyl group, or an alkylthio-substituted phenylgroup, and, (c) a solvent capable of dissolving the components (a) and(b); (ii) a step of irradiating the coating with electron beams througha mask after heat treatment, and (iii) a step of developing the coatingby use of a development solution after carrying out heat treatment orwithout heat treatment.
 17. A process for forming a pattern whichcomprises(i) a step of coating a photoresist composition on a substrate,the photoresist composition comprising(a) a polymer having repeatingunits of the formula: ##STR38## wherein R¹ is a hydrogen atom or amethyl group; R² and R³ are independently a hydrogen atom, or a linear,branched or cyclic alkyl group having 1 to 6 carbon atoms provided thatR² and R³ cannot be hydrogen atoms at the same time, and a combinationof R² and R³ being able to form a methylene chain having 2 to 5 carbonatoms; R⁴ is a linear, branched or cyclic alkyl groups having 1 to 10carbon atoms, a linear, branched or cyclic haloalkyl group having 1 to 6carbon atoms, or an aralkyl group; R⁵ is a hydrogen atom or a cyanogroup; R⁷ is a hydrogen atom, a cyano group or--COOY; Y is a linear,branched or cyclic alkyl group having 1 to 6 carbon atoms; R⁵ and R⁷ maybind to each other to form --CO--O--CO; k and l are independently anatural number (0.1≦k/(k+l)≦0.9); and m is zero or a natural number(when m is a natural number, 0.05≦m/(k+l+m)≦0.50), (b) a photosensitivecompound which generates an acid upon exposure to light, thephotosensitive compound being a compound represented by the formula:##STR39## wherein R¹⁶ is a linear, branched or cyclic alkyl group having1 to 10 carbon atoms, an aralkyl group, a trifluoromethyl group, aphenyl group or a tolyl group; and R¹⁷ is a linear, branched or cyclicalkyl group having 1 to 10 carbon atoms, an aralkyl group or an alkoxygroup, and, (c) a solvent capable of dissolving the components (a) and(b); (ii) a step of irradiating the coating with electron beams througha mask after heat treatment, and (iii) a step of developing the coatingby use of a development solution after carrying out heat treatment orwithout heat treatment.
 18. A process for forming a pattern whichcomprises(i) a step of coating a photoresist composition on a substrate,the photoresist composition comprising(a) a polymer having repeatingunits of the formula: ##STR40## wherein R¹ is a hydrogen atom or amethyl group; R² and R³ are independently a hydrogen atom, or a linear,branched or cyclic alkyl group having 1 to 6 carbon atoms provided thatR² and R³ cannot be hydrogen atoms at the same time, and a combinationof R² and R³ being able to form a methylene chain having 2 to 5 carbonatoms; R⁴ is a linear, branched or cyclic alkyl groups having 1 to 10carbon atoms, a linear, branched or cyclic haloalkyl group having 1 to 6carbon atoms, or an aralkyl group; R⁵ is a hydrogen atom or a cyanogroup; R⁷ is a hydrogen atom, a cyano group or--COOY; Y is a linear,branched or cyclic alkyl group having 1 to 6 carbon atoms; R⁵ and R⁷ maybind to each other to form --CO--O--CO; k and l are independently anatural number (0.1≦k/(k+l)≦0.9); and m is zero or a natural number(when m is a natural number, 0.05≦m/(k+l+m)≦0.50), (b) a photosensitivecompound which generates an acid upon exposure to light, thephotosensitive compound being a compound represented by the formula:##STR41## wherein R¹⁸ is a trichloroacetyl group, a p-toluene-sulfonylgroup, a p-trifluoromethylbenzenesulfonyl group, a methanesulfonyl groupor a trifluoromethanesulfonyl group; and R¹⁹ and R²⁰ are independently ahydrogen atom, a halogen atom or a nitro group, and, (c) a solventcapable of dissolving the components (a) and (b); (ii) a step ofirradiating the coating with electron beams through a mask after heattreatment, and (iii) a step of developing the coating by use of adevelopment solution after carrying out heat treatment or without heattreatment.